Some of the bigger outfits may expect more than say the smaller rancher types but I would say 10% or so.
Most guides really appreciate anything you give them, they do not expect every hunter to be able to afford a huge tip.
Get to know your guide, work with him or her and relay any issue you may have about your ability in the mountains and do what they tell you while hunting.
You'll be able to determine what they were worth. If they're lazing and do really nothing to get you on an elk, tip should reflect that.
Don't forget the cook, a tip would be most appreciated if food is good. Even $100 is appreciated.
When I buy what I want to eat I just go to a grocery store. I don't see any point to these Bwana faux hunts.
IF you just want some guy to point to it, hold the gun for you to pull the trigger I'd just take a side of beef and hang it on the fence. Get a lot more and better meat for your money.
You are really special.
Have been "guiding" myself for decades in Montana, along with sometimes guiding for an outfitter. If you've never done it, from either side, then you have no clue.
Plus, there are plenty of places on this planet where, if you want to hunt there, you must go with an outfitter/guide, by law. If you have no curiosity about that, well then good.
But if somebody else does, that doesn't mean they're "bad." In fact, have been guided by more than one outfitter here in Montana who asked me to guide for his outfit, one after our first day.
But just your comment, "IF you just want some guy to point to it, hold the gun for you to pull the trigger" is enough to tell you have no clue about what you're talking about.
