It is a business. Of course its easier and a lot more fun to play the gigs you like than the ones you don't, or you need. Easier to get and maintain your motivation for the fun ones too. Though we can become adept at hiding the dislike for the ones we don't like I believe it comes through at some point. Experience helps you keep that smile, even through the occasional negative comment we may hear that can throw you off. I've turned down undesired jobs and had no regrets.If you can afford that, both financially and for your reputation there's no harm. Nothing wrong with having standards. In the beginning I took everything to gain experience. Age and physical limitations changed that. Conversely, if you can afford to say no, beware that next year maybe you'll need it, and the job may belong to someone else by then.