I have been on about 5 guided trips total in my life and only 1 was a terrible time.

I think people have different answers depending on their skill level. Some guys want to be instructed on how to even fish correctly and some guys are just looking for something different than the same old water they usually fish. Personally, I have only fished with a guide when I have not been able to take advantage of certain water myself ie....Quinalt-Deschutes-Rogue or wasnt willing to donate several trips to learn a good section of river. I dont really need instruction, just a seat on the boat and a guy that knows his stuff and is fun to be around!
Number of fish in the boat is secondary to how much effort and knowledge a guide is willing to put in for your trip. The only bummer trip I ever had was when the guide completely disregarded our desires and did things his way--no compromise! I paid for one thing and got another.

I have always paid around 125-150 for a trip and never really felt that that was to much. Far away places take gas, lodging, time to learn and I think taking a guided trip is cheaper in the long run.

My .02

Crayfin