You pros out there - do you usually carry model releases around, just in case? Or only when you're on a shoot?
I always carry a few in my camera bag. Just simple ones. You don't need long winded ones. You can find them through google. Just edit to your liking.
When do you find yourself using them? And have people been reluctant to sign?
I have carried a couple for th last year, but have yet to take a picture of a person that would be useful for anything
I have a folder in my car with a few different model releases and property releases. I find that generalised/generic releases aren't very effective and therefore have a mixture that suit specific needs. They very rarely get used though except when the shoots are planned.
The only real time I might use them is I intend to make any money from the shot or if it is for any advertisement. I did some photography for the local physio therapy clinic for their brochures. There were images of clients using fitness equipment that we used in some shots that we had sign releases. From what I understand though, it never hurts to get a simple release signed regardless when that person is in a photo. If you feel confident enough that your images may amount to getting any kind of attention be it gallery or on-line sale of the print then it is a smart thing to do.