Ravilah said:
I was just wondering if anyone (specifically DMs) has ever found that by about level 10, most PCs have Spot/Listen checks so out of this world that nothing short of a shadowdancer wearing a Cloak of Elvenkind at Midnight has much chance of successfully staying unseen or unheard.
I take it you are using the appropriate range penalties on spot checks?
A 10th level halfling (or goblin, or other small) rogue with Dex 20, maxed out hide and an Elven cloak has a hide score of 4+5+13+5 = 27. Assuming he takes 10 (to keep the maths simple), then your PCs need a 37 even if he's right under their noses and the further back he is the harder it gets. Assuming he's 30 feet away (so he can still sneak attack) then that's effectively DC 40. [Ok, technically its DC 37 with a -3 penalty to the roll.]
If you really want to, blow two feats to get it up to 45.
If that is still a problem, include a distraction of some sort and the DC goes up to 50.
If your PCs are somehow able, at 10th level, to regularly make skill checks that are in the 40s then I suggest you examine their character sheets for errors.
However, if a player has, for whatever reason, optimised his character for spotting - for instance our party has an Elf mystic theurge with elf paragon levels, high wisdom and alertness (due to his familiar), who has an awesome spot score - then it is only right and proper that he gains the benefits.