Jim Burns wrote:
This is where a good airport manager or grandfatherly figure can politely
inform the offending pilot what they happened to notice. It's surprising
what a subtle hint between pilots can accomplish.

It's all in the way that you approach the person... If you approach them
in a confrontational manner, confrontation is what you'll probably
get... Which do you think is going to work better:

1. "Hey ****head, are you so stupid that you didn't know that this is a
lefthand pattern airport?"

2. "Excuse me... But, just in case you weren't aware of it, this is a
lefthand pattern airport. If it's not too much of an inconvenience for
you, would it be possible for you to fly a lefthand pattern from now on?
Thanks..."

Not that I have a problem with being confrontational though... It might
not be the best way to get things done all the time, but sometimes it's
necessary for certain situations...