How do you act with familiar local strangers that are dodgy

I stay on a road with a pub that has many dodgy types. Fights drugs common etc.

A couple of guys I see like every day as I walk past them.

I used to ignore them but they obviously recognised my face over time so couple times said “alright”. I said “alright” back.

I done that for a few weeks then was away so didn’t see them for a while when I came back I went back to just ignoring when I walk past them.

I dunno what to do for example if he walking towards me on road. When we walk pa’s near sure to nod say alright mate or complete blank them.

I mean i gues it’s same with any people but if it’s a guy I know similar who is student or stays same building as me I just say hi or whatever.

As these guys are dodgy people I not sure what to do?