Go to it and look at what type of water the guide uses....
Dead give aways are lunker structure and manicured stream sides.
If the guide's site is loaded with PUBLIC water...
Find a different guide.

Tip is optional....
If he shows you a good time and puts you on quality fish and numbers.
Tip should reflect that.

Also go to his fish area........
Look at how he handles the fish...

Look at what he percieves as a LARGE fish.

Have gone to many HOG areas and laughed at the size of fish.

If there are client testimonials.....
A good thing.

Make sure you match what you want from the guide.
If you want casting lessons........
If you want matching the hatch expertise......
If you want to learn how to read water.....
If the guide has permission to fish *Water Less Traveled*

Ex-guide here.
Did it for 2.5 years.
Finally quit because it was like:
"Going to a gold mine without a shovel."


ALSO: do a web search of the guide. See what other sites he/she frequents and see if person is respected.