For me, it’s when someone has only joined in the past year or two but has already made several thousand posts. Users like that are usually extremely obnoxious.
This so much this, I was going to say that the moment I saw the thread, but you literally posted it in the OP.
Forreal, people like that are either 1. obnoxious and wasting everyone's time as you said. 2. Trying hard to fit in by adopting the personality of what he/she/it thinks a kiwifarms user should have, like calling others spergs instead of smth like faggot or retard or even something more normie like idiot and dropping terms they just learned yesterday like ween and whatnot. You get a literal stereotype of what an outsider basically thinks a kiwifarms user types like. or my favourite numbah 3. Both of them.
What mental illness compels anyone to post here like it's twitter or some shit.
2 more red flags for newfags and oldfags aswell:
If someone has a furry avatar or posts exclusively in animal control he'll get banned eventually for being a sex pest coomer degenerate. Furry PFPs also tend to have the worst takes on everything.
/pol/tards and incels who hate fags, nigs, kikes, dykes, cunts, scrotes (femcels) or whatever else unironically like there's a difference between using a word and being a miserable worthless waste of oxygen who needs to vent about muh people problems all day long instead of just thinking about themselves. You can usually sniff them out by going into the Thunderdome (if

♂) or the Beauty Parlor (if

♀).
EDIT:
Ok 1 last more.
People who freak out easily from getting 1 bad sticker. Reversely, people who make a big deal out of a semper fi. I also notice these are the kinds of retards to just spam stickers just to annoy and for no other reason "oh I don't like that guy, I'm going to give all his posts a hat to show him". Some of them ended up eating a ban after they shat up a thread or they stopped posting altogether after getting a sizeable amount of hate on their profile. The only nigga who knows what he's doing with the sticker spam is Secret Watcher, stop trying to copy him niggers.
Another edit:
•Anyone who references how long they've posted here during the first 5 minutes of a petty argument
•Sticker Spergs
•Blatant /pol/tards who still think 2016 Alt Right™ talking points are deep
•Niggas and bitches who don't be fuckin (incel/femcel)
I earned that

FUCK!