If I'm in a public sitter I could care less who hears it. The smell isn't a concern either. Number one reason a public dump is such a gas is that there's never a doubt in my mind theirs are pooier than mine. One feels right with himself and with his maker, even though the glory lasts for a mere minute or two, when he gives fresh new birth to the foul aire of the otherwise unfortunates about him.
But once alfresco or at the office my tried and true method of cover up is to go near a group of people just after I've beckoned a nice one. In so doing who will know who laid it, as they will always blame each other?
If it's one of those where you crimp down as best you can, but to your dismay it exits with a boom, swish or pop pop pop, I'll rub my shoe soles on the floor until I get a throaty baritone b-flat out of them. Works every time if that squawk has a good tonal sonority. It's a consequence of practice.
And you?