Still the same for me. I still have no qualms on dumping inserts or consolidating expansions into the base game box and throw away the exp box. Making erratas/paste-ups is too much work for me nowadays, but I probably won’t mind using a sharpie on the rulebook. I just have to be detailed on what’s the condition of the game.
I don’t make any attempt to cater for “those types” who want their games to be pristine.
Well, before selling I usually remove whatever additions I made to the games. In case of Villainous (nobody wants it?) I removed the sleeves and my home-made insert because I still had the original. In the case of Periodic I left my home made insert in because the other one doesn‘t exist anymore.
I treat all my games with great care and I find that games with any kind of problem usually do not sell. Missing pieces or a box that already arrived with a dent immediately devalue a game.
I haven‘t been selling long enough. The only game I ever(1) had that I played enough it showed signs of wear was my original copy of Spirit Island and I gifted that to my cousin this Easter with my foamcore insert and the sleeves. (The wear was on the island boards mostly)
(1) yeah not ever… I am sure I broke a lot of stuff when I was younger. Some of my games from back then looked awful. I am talking about my hobby gaming period obviously 
No at all. I’m reasonably careful not to deliberately damage anything. Marking a card to update it is a bit too far me. I may consider sleeving with a note in the sleeve if the errata warrants it.
I’ve probably got 1/3 -1/2 of my collection sleeved (stuff that the kids play and/or stuff that gets shuffled a lot).
As others have said, I’m honest (and harsh) on condition and if someone leaves it because of a small box crease then it’s a not a person I want to deal with anyway. My experience says that they will ask for further discounts further down the line. I just wish we had the prevalence of the German parcel drop offs so I can post at a time suitable for me.
I did forget to remove the plastic dagger I’d got from elsewhere when I sold Dead of Winter, and I rather regret that. Oh well.
This struck us even at the time - this was UKGE 2018, the poster’s dated 2017, but that would still give you Terraforming Mars and Scythe… on a quick skim the latest I see is Splendor in 2014, and mostly it’s 1990s/2000s.
Tutankamun - One of Knizia’s average works. I prefer Bites from Board Game Tables
Portobello Market - the shared incentives are there but wasn’t as interesting as I wanted it. Again, got sold because I prefer other light games I already own
bit late to the party, but if you find a copy of roads & boats, @pillbox will probably pay your trip for you
Same. I got very annoyed when I bought a second-hand game and I had to remove all the cards from sleeves 
Especially because they were tiny cards! The sleeves must have tripled the amount of space they took up in the box.
I’ve definitely become more conscious of keeping things in good condition since I started selling stuff. I’ll keep the box in good condition and if it’s a game that requires a lot of handling/shuffling I’ll sleeve the cards.
That being said, I’ll happily chuck inserts and expansion boxes away after they’ve been squeezed into the original box. After all, I’m not running a warehouse here.
Recent sales:
Space Alert - It’s brilliant, it’s frantic, it’s very funny - but I struggle to gee enough people up to play it because it really requires a lot of energy. It’s a game I’d recommend to everyone, but alas I can’t justify keeping it around if I’m going to play it so infrequently.
MicroMacro: Crime City - It’s great, but has a short shelf-life. If it had been just that little more family-friendly we’d have probably given it away to friends or family.
Century: Spice Road - I like it, but most of the important decisions are front-loaded. The second half of the game sometimes feels like it plays itself. We prefer Eastern Wonders.
That’s the way I feel about Magic Maze. Great game if one’s in the mood for it, but very intense, and quite often not everyone at the table wants an intense game.
Detective City of Angels finally sold after several weeks on the classifieds. Not sure why selling an open but unplayed game at $40 off retail brought the low-ballers out of the woodwork, but it did, and it was a frustrating game to sell as a result.
I sat down more than a few times in an attempt to solo the game, and just couldn’t muster it. As an event game, the box was simply too big to retain for rare occasions. I probably could have leveraged it for a nifty trade at the next big swap meet, but my closet is pretty stuffed at the mo, and I wanted the space ASAP.
[EDIT] And I also forgot to post that I did end up selling on Coffee Traders to a friend. It’s still with me, and the hopeful idea is that I’ll deliver it to him ready to teach and play.
Sold, betrayal at house on the hill it’s a fun mess of a game that I have no real interest in playing again.
Totally agree with you on Century: Spice Road. We were really excited for the “Splendor killer” but ended up flipping it pretty quickly.
Same. I am still looking for the game that is better at Splendor than Splendor. So far haven‘t found it. Have sold 2 of my attempts at finding that game recently (Century Spice Road and Space Explorers).
Not sold but given away to a friend: Village Green—the solo for which I acquired it fills the exact same niche as the solo of Flourish: a 3x3 spatial puzzle with interesting scoring conditions and it is even the same theme of garden creation. I prefer Flourish because it has such a variable player count and the solo is more interesting with the „bot“ as a puzzle element. My friend loves his garden and enjoyed Flourish when we played it so I thought Village Green would have a good home on his shelves.
Funny enough, I think I wouldn’t mind adding Century: Spice Road to my collection, the two times I played it I really enjoyed it. Even without winning either. Which I hardly ever do at Splendor.
It exists! It is Splendor: Marvel. 
Is it though? Because I‘d love to have a Marvel version but is it really better? Because the Marvel Love Letter is NOT Love Letter and as we haven‘t managed to get it to the table due to unnecessarily complex extra rules… I am sure it is good but… it is not played. So how much rules variation is there in the Marvel Splendor?
Edit: And when we‘re talking about Splendor-likes and Century being one, then at least honorable mention must got to Wonderful World because that‘s really a nice engine builder but it adds in drafting making it more alike to 7 Wonders…
I think it is. It is Splendor with three changes. First, you play to 16 points, not 15.
Second, you must have a green token in order to win. You get a green token by purchasing a level 3 card. You can only ever have one green token and you cannot lose it or use it for anything.
Third, the equivalent of the Noble tiles has one that is always included: the Avengers Assemble token. A variety of the cards you purchase have Avengers symbols at the top (with some of the more central Avengers having two symbols on their cards). The first player to collect 3 of these symbols takes the Assemble token. But, the token from that point forward will go to the player with the most Avengers symbols. In ties, it stays with the current owner.
That’s it. The only downsides are the tiles are double sided, so randomizing them is a bit trickier than base Splendor, and the chips are different colors, so no, that yellow chip is not wild, wilds are black, stop thinking gold is wild, Chris (that’s me).
I like the changes, as it adds another layer of strategy to the game without really adding much complexity. Two of the changes can be done with the base game, just playing to 16 and making it necessary to purchase at least one level 3 card, but it’s the moving Assemble token that really changes things up, IMO.
That sounds tempting indeed 
thanks for giving me some insights
This isn’t really a sell, but we sent my folks home with our copy of The Fuzzies. They really wanted one for themselves and figured we should save them the post-SUSD headache, so we’ll source another copy for ourselves eventually.