Boards
with flushes on them are very scary to say the least when you don't
have it. In addition, when a person simply flat calls your bet
after the flop, and the flush card comes, you have two choices:
Check and lose, or bet to see if you have the best hand. If
they come over the top, you lay it down (this assumes you still have
chips to play with and don't pot commit yourself). Below is an
example...
