I definitely perform for those who look like they want to be entertained and not heckler type people.
I agree. But when you're being paid to perform, such as in a restaurant, you shouldn't just choose not to peform for someone be cause they look like a heckler or like they don't want to be entertained. You are being paid to entertain customers of the restaurant. If you're not being paid, then so be it. Peform for who you want. But I still like viewing the heckler as a challenge. Through this I continue to improve on how to stay in control in various situations. If you choose not do deal with a heckler before they heckle you, then you will never learn how to deal with them when it is totally unavoidable. That kind of feeling won't be good.
Keep in mind, there are some people who just don't want to be bothered with entertainment (bothered?). And many times you can see that before you ever approach them. I have sensed this many times from people prior to performing magic at their tableside. But I don't let that change my attitude about performing for them. Usually when I'm done with them, they are applauding, laughing, and asking for more. THAT is truly a reward. However, be sure to recognize those rare times. The ones where a boyfriend and girlfriend are out to eat only so she can break up with him. You may approach them, but it doesn't usually take long to see that you will not be peforming for these people. This has actually happened at, of all places, a Friendly's restaurant. Seems like the wrong place to be breaking up.
Anyway, good luck to all.