[Nyquiz]

I think a little bit of the results are seeping into your post. There is almost no way I know what someone has with 100% certainty. You can however put them on a hand range and then assess how likely it is that the person has a particular hand given that range.

If you know for absolute certainty that this person knows you have a straight and is in no way bluff raising you then you're beat, your read takes away the % chance that this person could be bluff and that they have a lesser hand.

I try not to make expert lay downs in hold em' even in games like 15/30- whatever, I look for spots where my equity or odds really suck and I lower my variance by folding my hand in those situations. If you are continually looking for spots to make miraculous laydowns, you will find them, and then hate yourself when you keep totally misreading your opponents hand strength.