With me, in Berlin everyone would speak English.

In Warsaw and Wroclaw, if I was brought in by one of the group, the whole group would speak English to not be rude. If it's random people, they wouldn't. Single guys or girls not in a group will speak English to you if you're hanging out with them.

I think it largely depends on who it is you're dealing with.

"uneducated" people and the elderly will be less likely to speak or wanting to speak English (cashiers are the worse, in my experience). Most young people will speak English. Programmers and startup people all speak English. Doctors speak English, etc.