Haas is a mental muppet with a nice backhand
The two most intelligent players would be Federer and Murray who demonstrate considerable variety, change of pace and strategy to defeat their opponents
The dumbest IMO are 'you know, it's like this, no? you know, it's like that? you know, i sound like a moron and more than likely am, no?' Nadal and (at least in a tennistic sense) the 'hit every ball for a winner' James Blake
Nadal demonstrates that a lot of player's IQs get lost in translation. Nadal comes across as quite articulate in spanish.
I would say Federer, he has a tennis brain but also handles the media better than anyone else.
On the whole you would have to say that tennis players are smarter than, say, footballers... I mean they'd have to be.
Rusedski would have to be one of the dumbest. I remember the time he shot his mouth off about how much he loved movies, proceeded to get his specialist subject completely muddled, then got all stroppy.