Here are some of mine:
emojis on listings or social media posts
When I’m interested in buying something but the pics have hairs everywhere in them and general yuk especially on carpet pics. Even worse is pubic hair beyond totally off putting. Blurry pics for sure and sellers who only take one pic and sometimes it’s just the back pic no good to me I’ve never ever bought just a back pic item ever.
Vending is not a promo set, it’s just a goddamn set. Plain snd simple.
TPCi packaging and products.
So much wastefulness it’s incredible.
When people conflate low pop with rarity.
Social media promotional monologues à la “Praawduckt inv3nt0ry dr0p 
, The Praawduckt is , The CommuniTEE, pr0m0te the brAnd, gr0w the brAnd 
, For the CommuniTEE 
, Good/Bad for the haawbEE, Pr0m0te the haawbEE 
, For the love of the haawbEEEEEEEEEEE 
, love to the c0mmUniTEEEEEEEEE 
”
Sounds like a mixture between Sunday School/AA and some guy with a toothbrush moustache doing retail inventory of washing machines. It’s why I never check Facebook anymore.
Buyers telling me that a seller/webpage is selling the same card I’m selling at lower price and demanding me to lower my price too if not, I’m ripping him off.
Usually in such cases, I’ll block that buyer and/or tell him to “pls go ahead, you like his pricing so much, you should buy from him”. 
People selling things at lower price maybe got QC issues like crease, crimping, scratch, wax blob or whitening.
Promote it on @tcgbulls 
Cheers!
People who yell “let’s f’ing go” when they open packs.
With the brand itself: when Gen 1 pandering acts like complete evolution lines don’t exist for the sake of the “original 151.” Acting like Crobat doesn’t exist, or all the Eeveelutions, absolutely drives me insane. I get no satisfaction from seeing “the original 151” all together, I just see a huge incomplete list of Pokémon with which I have a 30 year relationship. Give me the full lines or give me death.
With the hobby; when people say “don’t store cards in binders.” This is offensive, to me.
Crypto being promoted along with cards. Like I’m not trying to buy into your coin you created yesterday.
Overuse of the term “grail” in listings
“Best price gets my money” - nope, try best offer gets my card
“I want to buy for my personal collection” -stop wasting adjectives, its just collection
“I am picking up positions in Battle Styles” - this suggests it is actually investible and not something 10,000 other people are already doing.
TLDR - stop saying personal and positions in Pokémon
Underexposed and blurry eBay pictures.
8 week delivery times from Japan because of Covid, when other Japanese sellers take 2 weeks.
Sellers who upload pictures of 5 of the 6 booster box surfaces. 
Big difference in delivery times were sellers who had the card in hand vs sellers who had to find a copy locally in Japan for a low enough price where it makes sense to continue the sale. It was a shame seeing some take 4 weeks to ship.
“PC”
“Would you take xxx?” message on a best offer listing
Calling every stranger ‘man’. Usually followed by some annoying message.
Example:
Posts card
[In DMs] Hey man! Congrats on the pickup, that’s huge! Mind if I ask how much?
When people ripple shuffle cards, when they do it to their own cards it annoys me a little but when they try to ripple shuffle my cards is when I lose it.
Also when people send out singles in a top loader and they tape the top of it. I get that they are trying to prevent the card from coming out but it is unbelievably annoying to try and get the tape off.
Tape is the worst. Only one that’s reasonable is blue painters tape.