question about the backdoor

[When2Holdem]

okay so heres an example: you are in the bb. under the gun raises preflop and everyone calls (extreme example). you call the raise from the bb with

6 [img]/images/graemlins/spade.gif[/img] 7 [img]/images/graemlins/spade.gif[/img]

flop comes

K [img]/images/graemlins/diamond.gif[/img] 5 [img]/images/graemlins/spade.gif[/img] 2 [img]/images/graemlins/club.gif[/img]

sb checks and so do you in the bb. original preflop raiser bets and everyone calls around to you.

now with 15.5 big bets in the pot and it is only one small bet to call, with 29:1 pot odds it seems obvious to me to call to chase a backdoor straight or a backdoor flush and just see if you can pick up a good draw on the turn. am i correct to say to call there? if so, the question from me then is at what point does it become correct or incorrect in more realistic examples to chase the backdoor draw?