well... since this was such a popular topic

It's not a great situation to go for an implied-odds draw.:

1) it's an unraised, A-high flop.
2) draw is not particularly well concealed. It's not a likely draw but it is apparent to the eye.
3) perhaps most important, Opp is PASSIVE. If opp is laggtard or the type who frequenly tries to push others off hands, chasing the draw is more likely +ev.

As played:

I lead for something like $6 on the turn; flat called. River was a blank. I lead for something like $10 on river. Flat called. Opp turned over A4... a pity he didn't raise the turn but oh well...