What is the unwritten "protocol" when we spot other counters?

I'm primarily talking about unknown counters that we "discover" while scouting tables, let's say. I know that we should NOT play at their table, if possible; this is a common courtesy. What I do not know is...Do we pretend that they are just another gambler and go about our business? If we approach them once outside the casino's cameras and security, is this considered bad form? If it's not then how do we open up a conversation...Do we "come out" first? Perhaps someone can set me straight on this matter, and here's my thank you in advance. 49.