It depends on the location. I've walked past bullies from former workplaces at different times and on the one occasion I took pleasure from the fact the one looked sheepish as if he felt a bit guilty and another I pointed him out to the person I was with in the supermarket as he walked past us (seemingly oblivious of me) and said what an obnoxious **** he was loudly but all he did was put a mock shocked expression on his face as he walked on. This type of reaction made me feel more worked up and wished i could have done something physical to him. I did feel as if I wanted to react more strongly but felt like the power dynamic where I was the bullied person again came back and I felt weakened by it.
Sometimes I fantasise about being in a situation whereby I have something one of my past bullies wants or I have the power in some kind of interaction, like them wanting to buy my house and me being able to say '****, off I'd burn this house down before I sold it to a **** like you!' Just some way in which I could get even and have the power or just have my say. I generally just loudly point them out to the person I'm with though, although it doesn't happen often.
Sometimes people I've just known in the past have glared at me and acted like they hate me for some reason, as if to say 'Don't even think of speaking to me!' and I used to feel cowed by it but these days I'd give them a glare back of nuclear proportions!
I've noticed that most people are often on speaking terms with their bullies which always confuses me as surely a bully is someone who doesn't want to pass the time of day with you(?)