[DrMontalban]

As a player who's been up the 525s there are VERY bad players at all levels.
The 55 players usually have some knowledge of the game, (ie. know what pot odds are), although ive seen some play at every level that is mind boggling (ie. calling all ins with 22/33/44). I saw an all in called on the bubble with 44 @ the 220s today by a solid, winning player.
I would say the jump from 110s to 220s is the biggest regarding toughness; my toughest games have been at the 200 level.
I would say there is on average 3 losing players at each game up to the 330s, usually 1 or 2 players who REALLY REALLY *REALLY* shouldnt be playing such high stakes, as well as 1 or two who are underrolled/skilled and are trying to make the money from a bad run back (if they win, they often move up in stakes as they see themselves as a better player and if they lose... it can get ugly. I've learned from this problem first hand after a 4-figure loss or two this summer.)