I do think this site can be inconsistent with its deletions and warnings. I have been warned regarding personal attacks before where I genuinely didn't think I had been notably harsh, rude or personal, yet seen other posts I thought were bloody vicious left to stand. I think the line between stating your opinion and personal attack can be blurred or moved depending on circumstances. I think people cross it without meaning to as well. I have.
I have since tried quite hard to word things in a way that would not constitute a personal attack. It can be hard to get right but I think it goes a bit like this....
"Uppity fuck" - personal attack.
"I think you're being uppity" - ok.
"Goady fucker" - personal attack.
"That post was deliberately provocative" - ok.
I don't think you're really allowed to name call or swear directly 'at' people. Even if it is (in your mind) justified. It's considered a personal attack and breaks the talk guidelines. I don't think they're the only way you can personally attack someone, but they're both a no no.
I don't want to end up banned or suspended so I try to keep things fairly neutral. Sometimes I get a bit impassioned and write something that sounds fine in my head in my own tone, then bite my nails worrying about it afterwards. It's quite confusing because as I say, I have seen some stinkers left to stand. I do think how popular the poster is comes into play sometimes. A lot of it depends on whether or not the post is reported.
Best to err on the side of caution in my experience. Not always easy.