The only place I've been when BYOC was necessary was an R&T in the Upper Midwest, usually L1 only, and my provider was offering L3 service under the radar.
Afterwards, she wrapped the spent condom in a tissue and placed it in my pants pocket, after asking whether that was OK. She didn't want management to see the evidence. Kinda gross, but that's where we live.
Anyway, I go BYOC because I generally don't like the standard condoms offered at most places. I find they are too small, too tight and restricting, too thick, too uncomfortable, and generally detract from the enjoyment compared to what I can pack in.
And rainman is right, setting out your tip and a condom at the outset obviates any negotiation, saves time, and avoids the need to speak any incriminating words that might be overheard (linking services to $$).
I only make this play if I'm pretty sure it will go over well: if I've been there before, or I'm sure from reviews that it is an L3-friendly place.