Is this a "bad beat" or just poor playing ?

[Dalek]

In early position, 66 is really too weak to play unless the table is really passive. Even if this is the case you should be able to play well post-flop and you should raise 3/4 x BB from UTG.

When he min-raises just call. Fold to the flop-bet. It is very likely he holds an ace and the pot bet is bigger than most players bet when the are continuation betting. You got lucky on the turn and the shove was correct because he has been playing strongly making it likely he will call. You got unlucky on the last card but the hand was played quite poorly.

BTW, i read something about it being difficult to fold a full house. You should almost never fold a full house, especially at lower stakes. Its almost never +EV.