I've hired a few different guides over the years. Usually it was to get a little "bump in knowledge" of that particular body of of water and/or recent patterns etc. I do tip them, usually around 50$ per day.I have actually had guides reduce their daily rates when I've been a repeat customer. I'd rather have that and allow me to tip them extra, than have the industry just add it to the up front costs. There have been times when (a) my boat was unavailable to me (b) had multiple people on a trip(needed another boat-experience) etc and most guides are instructive,friendly people.
I think it's a common courtesy to tip people that are providing me services. And yes I have tipped auto mechanics,a plumer,and a few other people before, that don't usually see any. Those instances were for what I perceived as special work/effort etc. If an individual doesn't feel the need to do so, well that's his perogative. I also have not tipped a guide once. He didn't do a good job IMO and didn't deserve one. He also shorted me over 2 hours of fishing time. I don't use his service anymore.
I also had a guide(who posts on the WI fishing reports) not even show up to the dock. Called him to find out he thought we had canceled but realized it was probably the "next days" client. Said he'd be there in 20....after 1/2 hour I left and didn't bother calling again. I haven't singled him out(in public) but I tell my friends(and other potential clients) to avoid him. I've heard similiar things about him from other sources also. I imagine he won't have a very successful service. Thankfully it was a last minute trip and I didn't pay him.