1: Hi Welcome.
2: There are 3 enemies, and each have a 25% chance to spot you every time they attempt. That means every round they get to try (read: every round you are there scouting) there is a 60.625% chance you are spotted. Since detection = death, and one round is the minimum type possible, it's clear to see that even under the best case scenario, in which the stealther has a bit of an advantage there is still a greater than even chance he is not coming back. Treantmonk fails a lot, but when he referred to the scout as "the Corpse" he was absolutely right. Would you prefer 5%? Fine, the detection chance per round is about 1 in 7. Now consider that it likely takes you more than one round to get in, look around, and get out and the only conclusion that can be drawn is that I am exactly right - you either throw the enemy straight off the RNG by having no chance to detect you, or you auto fail. If there's more than three enemies, that's even more chances to fail.
3: I'm sure the enemy won't get suspicious about any fog or smoke coming up out of nowhere. I'm sure they will never mow their lawn. At least pretend you are serious.
Ok, seriously, without CoP (because all I'm ever going to answer to that as a GM is "maybe"), how do you scout ALL THE FUCKING DAY with magic? Because that's just the time when not being able to can really fuck you up. For instance, sometimes even a high-level wizard will have to walk to places. Well... not necessarily walk, but, NOT teleport. And if just for the reason that he doesn't know yet where he's going.
Well for starters, you get a non douchebag DM, who doesn't randomly herp derp and make spells not function as described. Once you have completed this step, and it might require one or more folding chairs, here is the most basic measure you take:
*Wizard writes a list of spells, the length is equal to the number of questions he can ask - 3*
"Which of the spells on this list will be most important today?"
Repeat for second, third, etc until you finish the list.
"What is the most dangerous opponent I will face today?"
"What is the second most dangerous opponent I will face today?"
"Will I be ambushed today?"
Might need a second cast for follow up questions, and to get the 88% right answer to something more acceptable. Still far better, and safer than sending in the corpse.
It's just like this: Every time when when I've played, and there was no scout, we were ambushed. Every time I've GMed, and the PCs didn't scout (well, they also didn't do other things, but considering there were often days of travelling involved, and the levels weren't that high, there wasn't that much they could do..) they were ambushed, too.
So, short of playing a Binder, how do you ALWAYS know what's on the road ahead of you?
Translation: Herp derp, I don't like that the PCs aren't scouting, so I'm going to jump them. I'm also going to pretend the scout won't get automatically annihilated if he tries.
Also, it's funny how every "stealth isn't worthless, honest" thread assumes that all guards are completely fucking incompetent. Because the moment they get remotely competent, or try at all you start losing all the time. This is especially true when the "completely standard scout" uses the very same things that auto negate them when used against them.
For example:
Mindsight: Auto lose, Darkstalker does not block, anything with telepathy will have this if allowed. No workaround.
Touchsight: Auto lose, Darkstalker does not block, anything with psionic ability and a high enough power level will have this. Only workaround is being incorporeal.
Lifesight: Auto lose, Darkstalker does not block, any undead will have this. Only workaround is being undead yourself.
Some of them get around one of these, but not all three. And that's just the auto lose stuff that gets you even after you try.