When I was collecting Roulettes years ago, I always let the house know my intent and why, along with mentioning I trade with other collectors around the World and that produced a half nod which I read as an "Oh" many times.

There have also been responses here that flashing our membership card had good results.

The few houses I played in the Bahamas also knew what I did and, since moist of them were Brits, I would always bring along some high-denom, obsolete plaques which they enjoyed seeing and commenting on.