I have been able to find some good titles I want to import from
overseas, but a question has been arised about these being legal to
import and resell here in the US.  How do I know if they are bootleg? 
How do I know if they are legal in the US?  What do I need to find
out?

The topic is referred to as IPR - Intellectual Property Rights,
and U.S. Customs has a brochure on it.  Chances are
that in large quantities, only the manufacturer or someone
who represents them will get permission to import.
Customs will have the right to seize your goods.
Please check this out and let's see what the better
details the researchers find.

There's a lot of bootleg stuff that comes in from the Far East.

A major problem is quality and (so I am relaibly informed) such stuff
stuff creates dissatisfied customers ...

In my opinion, it's best avoided.