I cringe when I see excessive netspeak or people posting in "pretty" colours and/or playing with the fonts when regular fonts would have done just fine. Or in the case of ITIL, Japanese where just saying the damn words in English would have sufficed ("My apato costs sanman per month" *eyetwitch*) But whether I'd say anything about it depends on the nature of the forum. On some forums that kind of thing very much frowned upon, but in other places, the person who thinks people shouldn't do it is the one who's in the minority, so it's bad form to say anything.

Also, ironically, as a moderator on ITIL I actually feel less able to tell someone to cut it out, because my feeling, and I think the general feeling on there, is that mods shouldn't be petty, and while netspeak and excessive and gratuitous Japanese can be annoying, it's not on the level of, say, flaming someone or posting racist comments. So quite often there'll be stuff where I would have said "STOP. THAT. NOW." as a regular member, but as a moderator I feel that it would be a bad move. So I just leave it. If it's really bad the regular members tend to jump on the poster anyway.