We tend to use it when we don't want to commit ourselves to saying something about someone, because we don't want to say something that might be wrong.
"He seems like a nice person, based on what I know of him so far."
"He seems mean, when you look at how he treated George."
We don't want to say "He is a nice person" because that's a very concrete statement, and we might be wrong - or because we just don't know for sure that he is yet.
We use it a lot for being negative about people too; I think that might be because we don't want to insult someone unless we absolutely have to. It seems nicer to say someone just "seems like" a mean person.
So it's just as correct as to say "he seems a mean person" or "he seems to be a mean person" or "he seems mean"?
Yes, it's OK to use a construction like "like" or "as if" after seem, or after the verb look - but oddly enough, we don't use it after appear, yet they are all partial synonyms (although not perfect ones).
I hear this construction sometimes but it sounds incorrect to me.
I'd really like to hear your opinions about it.
*Not a teacher
"Seem/look/sound/be/feel/etc like" is perfectly correct and very common in spoken English in particular; you could bump into it when you chat on the Internet as well. And as Tullia said earlier, like, as a comparative, is also used not to directly say to someone that s/he is a mean person. Like attenuated the meaning in your phrase for instance.
Last edited by philadelphia; 24-Aug-2010 at 14:45.