Failure to protect a vulnerable hand on draw-heavy boards
-Since they are giving us very good odds to draw-we just flatcall
-Valuetown thin when we hit our draws

Failure to build big pots with strong made hands
-We get to see a Cheap showdown value which is good.Calling would be just as good here.
-Never raise their decent size bet

Slowplaying in incorrect situations
-Fish would love to C/R the turn a lot.
-B/F is the best to exploit this.

Bet-sizing tells (small flop leads, large overbet shoves, etc...)
-Yet again.B/F seems to counter large when we are not sure we are behind or not.
-Raise when we sense small flop leads-weakness
-Fold/Call when we sense strength

Another thing i would like to mention is a huge huge 3bet sizing
i.e Hero opens 4xbb,Villain repops to 20xbb