I watched a set over set one time and said "ouch" I have lost a few when 3 of us flopped sets and I had the middle set.

So, I set down to try to figure out how likely a set over set is. I am sure that there a players that are better at odds but here are some things to consider.

Lets say that there is a raise and the players will only play pocket pairs 99 and up when raised. You have 88. The odds of getting a specific PP is 220-1, 9 players preflop, 6 PP (99 - AA) so 220/6/8 = 4.5:1 that someone has 99, TT, JJ, QQ, KK, AA. About 20% you are beat.

Now the odds to hit a set are 7.5:1 - if you hit your set. The odds that he has a bigger pair and hits his set is something like .2 * .12 *.12 or about 346 to 1.

I am sure that my caculations are off but you get the point. They are pretty long odds. So, I would discount a bigger set being out there most of the time.

I saw two player with A9 both flop a full house with A99 - I have seen this one time in playing for 3 years.