For my mind, the real marker of a true Christian teacher must always be their adherance to the Word of God. Forget the hotel rooms, forget the cars, forget the money. Those things might lead us to a conclusion (and we may be justified in those conclusions - should Benny Hinn live in the lap of luxury? Probably not, as someone already quoted "everything is permissible, but not everything is beneficial"), however, they lead us to a conclusion that, ultimately, isn't the point.
If we're going to take issue with Benny Hinn, it shouldn't be on the basis of his overtly charismatic personality, his slightly ridiculous hairstyle, or even the money he makes every year, it should be on this: does he teach and preach Christ faithfully?
I know what my answer to that question is. I feel that Benny Hinn has made his stance very clear. He has made repeated false prophecies (after all, didn't He say Jesus was going to appear at his meetings in Nairobi, Kenya?), has claimed that the Godhead is nine-fold (father, son and Spirit are a trinity "each" (a claim he retracted, then made again, bizzarely)), and many, many other things, which I won't document here (I'm sure a brief look around the forums will reveal many other threads with this information).
For me, Scripture is clear. If someone makes a prophecy and it doesn't come to pass, they have spoken presumptuously and are a false prophet - the Lord didn't speak through them! This being the case, we should have nothing to do with Benny Hinn.