It's literally just a packet with the ssid and related info in it, shouted into the void. It becomes an issue if you shout so much that other people's traffic is effectively jammed, otherwise, have fun.

Maybe you could get a wifi channel to yourself by adding a bunch of fake AP's on the same channel, and having your neighbouring routers automatically switch to a "less crowded" channel.

They might use more heuristics than just the number of ssid's advertised on a channel though.