Try this i was checking it yesterday with the same questions.
Hitting Flops With Middle Suited-Connectors in Hold'em Poker

Basically you hit a spot of enough equity to play with about 40% of the time (when you flop OESDs, FDs, combo draws, two pair etc). When you have 33 it's completely unplayable 90% of the time because when you dont hit you're in a spot where you likely have about 10% or less equity.