If I am actively hunting a stand, I won't P from it.  If I have to, I'll taker in a 2 liter bottle or something.  However, as a general rule, i don't really believe that the deer are that turned off by our P, so if I am walking through my area, I have no problem with doing it.

I don't really like to go in the stand, but I have done it in the past and have had deer come in and they didn't seem to notice it. Then again, I have never seen a mature buck from my stand after I have peed out of it. So, like I said, only if I absolutely have to do I pee out of the stand. 

I think it all matters on the stand you are hunting.  I would imagine that it would affect the whitetail hunters more than us that chase mule deer.  I read about all the scent killers and different avenues that people take to get to their stands so they don't sent their scent towards the deer they are after.  I would imagine that if you are going to all that trouble, it's probably not a good idea to leave your scent lying on the ground at the base of your stand that you are hoping to harvest the trophy in your dreams from.  Peeing from twenty feet in the air actually would allow the scent to be temporarily spread out over an larger area also (kind of like a mist from a can of deodorizer).  But, if you are strictly hunting the wind, and you know the deer are only going to come from up wind, I wouldn't imagine it would negatively affect your chances.  Of course, the day our prey always do what we expect and hope they will be a first.

As far as it is for me, I hunt from the ground and am pursuing more non-patterned mule deer.  I'm either a spot and stalk guy or hunt out of a ground blind.  I don't worry about where I pee when I am on a spot and stalk because my path usually leads me into the wind.  If my plan is to hunt from a ground blind, I make sure my bladder is empty before I make my stand.

I make it a habbit to pee at the truck everytime before i walk in. If I HAVE to go while in my stand I'll get down and dig a hole and pee in it then burry it.

  I have a video of a guy demonstrating how to call deer by only using his mouth - no manufactured call. Part of what he advocates is P-ing from your tree stand. He claims that it mimicks the sound of a buck urinating here and there to mark his area.

  Prior to seeing that, I always took a bottle with me, but since then I haven't. I don't think it makes any difference.

I try not to make it a habit,but when ya gotta go,i use'ta do what sumone menttion'd,dig a hole with foot an bury it....After read'n bout the guy that used his P on mock scrape it got me to think'n how can smell of P tell u where it's from. P is P ant it.....it STINK's no matter where it came from...Where's the Smiley with him hold'n his nose?

On another site a guy said he peed on the deer's head while under his stand and he said it didnt bother the deer.  I don't think it matters but i still don't do it.