I'm with you on that. It's not so bad if their English is good enough to have a conversation but I'm not a big fan of giving lessons at the park when I'm out with my kids.
However, I do it.
Sucker, I guess.
The big thing for me is students asking me questions when I am in a book shop or in Pizza Hut. It's very annoying for me but they have been given it as homework from their teacher. They ask some basic questions which takes about 5~10 minutes of my time. Sometimes I do it, sometimes not. I guess it depends on the type of person I am. Then sometimes they ask to take my photo as proof and I always refuse that. God knows where I could see that photo again!!
It's the teacher I want to kill!!