I have seen people listing PS2 games in the PS3 category, technically PS2 games can be played on *some* PS3 models (in the UK this means the 60GB model only at present), but when I look down the PS3 listings I don't really want to see PS2 games.

I would consider reporting them, but I wouldn't want to be responsible for driving people away from eBid because of picky things like PS2 / PS3 inconsistencies and people who argue the toss.