Can someone be manipulative without realizing that they are being manipulative?

I think most manipulators don't realise who they are at all, a lot of them are narcissists who think they are "right" and seem to think they are actually doing you a favour...

Some are just lifes ***** who will do whatever it takes to get their own way and know exactly what they are doing.

Absolutely. Some people are seriously good schemers. So good that they dont have a conscience.

Of course even the most sharp can be outwitted!

Sure. If they lack self awareness/honesty with self.
We will think others are, but no one wants to think of [i]themselves[/i] as a manipulative person.

Yes. Deception can run extremely deep.

Absolutely. Happens to a lot of people.

Yes. Be careful of those people

yep

Absolutely. It takes someone telling them and them actually looking within themself to figure it out.