Nah, always ask. (Unless the dog has already approached you etc). Some dogs aren't sociable, don't like kids, don't like other dogs, are defensive on a lead etc etc. I'd always ask.
I had a really lovely recently rescued staff/boxer cross come up to me in the park this morning. He was really friendly with me but the owner explained that he is very snappy with men while on the lead. Has been known to draw blood etc.
Nah, always ask. (Unless the dog has already approached you etc). Some dogs aren't sociable, don't like kids, don't like other dogs, are defensive on a lead etc etc. I'd always ask.