outs for straight vs flush draws

This is a total newbie question.... What is a "straight vs flush draw" exactly, and why does it have 6 outs?

I'm not sure what you mean here but this the basic outs chart.

An open-ended straight draw gives you 8 outs.
An inside straight draw gives you 4 outs.
A flush draw gives you 9 outs.
An open-ended straight flush draw gives you 15 outs.
An inside straight flush draw gives you 12 outs.

An easy way to figure you're % to hit is to multiply your outs by 4 on the flop and 2 on the turn. Figure out your pot odds and implied odds to make the decision on whether to bet/call/raise/fold.

additionally, if you were to have an open ended straight draw but there was also a flush draw on the board, then 2 of our outs are potentially tainted and thus we only have 6 outs as opposed to 8.

ie, on a board of 5h8hKc with 6c7d, we are drawing to 4c,4d,4s or 9c 9d 9s since the 4h and 9h would both give a flush draw a flush which would beat our straight.

Originally Posted by JKDS

additionally, if you were to have an open ended straight draw but there was also a flush draw on the board, then 2 of our outs are potentially tainted and thus we only have 6 outs as opposed to 8.

By re-reading OP's question, I think this is exactly what he was asking.

A straight versus flush draw means you are on a straight draw (8 outs) and the villain is assumed to be on a flush draw (9 outs). Your draw only has 6 outs because two of your 8 outs will complete villain's flush.

Ex:

you - JdTc
board - 3s 9h qh
villain - assumed to be on Ah 4h (nut flush draw that doesn't interfere with your str8)

You can hit : 8c 8d 8s 8h, Kc Kd Ks Kh - 8 outs
Villain needs : 2h 3h 5h 6h 7h 8h Th Jh Kh - 9 outs
But, your 8h or Kh completes his flush, so those are "bad" or "dirty" outs.

Remember, as well, that "dirty outs" (I like to call them "doubts") still may be outs. In other words, it is very rare where you can confidently say that a flush draw comprises 100 percent of a player's range.

So these dirty outs count for something, even if they are not as good for you as your 3 or 6 clean outs are.