I have never used him but know 10+ people personally who have been ripped off by him.
I am wise to tricks in Turkey too, and I don't think he has a chance of ripping me off. But I won't ever use him, based on the fact that I know 10+ people who have been ripped off by him and I will not give business to dishonest people.
There is simply no need to - Dikmen for example I have used for 12 years + without incident, and without ever once hearing of an incident - and they are just a few steps along from "Colin". Oh, and as Jacqui mentions, work legally as an official licensed change shop - not hovering around outside their shop, acting like a pest to every single person who walks past.
He's a cheat and he is bad for Fethiye - not that he is any way bothered by that fact.