I was always one who, if I saw a sign along the lines of 'No Religious Callers', I'd turn around and not bother them. Did work with several "zealous" ones though who always argued "we're not religious callers".
On another topic...
The version I heard was that John Denver asked witnesses to leave at the beginning of every concert.
I actually knew a sister once who claimed she was at a John Denver concert and heard him ask for any JW's in the audience to raise their hands... then tell them to leave. Still wouldn't call it confirmed though as this sister wasn't always truthful about her claims.
Oz Radio Announcer John Laws used to announce over the radio (his program is aired nationally) about witnesses working certain suburbs. People would ring in and say they live in xyz area and they just got called on... he'd broadcast a warning on his show. That one I can vouch for as I've heard these warnings myself.