I think they are regarded more as cartoon characters...especially since some americans are like "WHAT?? JAPAN HAS MUSIC???AND ITS JUST AS GOOD AS OUR MUSIC???"
anyway, this is funny cuz my friend and i were talking the other day and he said that he was watching their show, and he goes "Japanese music is stupid..." and i was like yeah...okay....anyway, when they first made their debut here, a critic in our newspaper reviewed them and it wasn't a very good review...he compared them to screeching cats, and said they were very annoying, and that he didn't like their "pop" style...although i thought they played rock music...
i don't think anyone really regards them as singers, as said ^^ by someone, i haven't seen their cartoon too many times though, i know it comes on cartoon network, so you know adults aren't going to take them seriously...