I agree with Zack and Al / especially when it comes to trout and more to the point, fly fishing guides.
( I admit I know nothing of hiring or being guided by a bass fishing guide )
If a fly fishing trout guide intends to fish with clients he is not much of a guide in my book. He is poaching the clients fish and getting paid to do it.
That being said, near 100% of all guide trips I've ever done, the clients have always asked me to fish toward the end of the trip. All in fun, just as Zack pointed out.
I also wanted to say that I was never one to cast for my clients. I was hired to help them fly fish and learning to cast is part of the gig. It can even turn into more fun than actually catching fish, as in how it is for myself. I prefer to have a great day flycasting to a bad day of flyfishing.
One time in Colorado I was shown a 'guides hook' made by Partidge. It was a standard dry fly hook with a regular eye to tie your tippet to. Similar bend as in all hooks - but where the point should have been, there was another eye! He gave me a couple to try out and I found it fun to hook a fish and lose it every time, no matter what. You just couldnt hang onto them at all. I have some I'll dig out if anyone wants to see.
best fishes, Brian