You can't turn down a commission.Well that's true but I won't paint your cat in front of your house or anything that has to be realistic or that I am not interested in.
The other side to that is that as an Artist new ideas and challenges open you up and broaden your horizons and can lead to opportunities that were not there before.
So generally speaking I like them .
They can throw you out a bit but that's not a bad thing and because they are set to specific agreements you have made they can be a bit wooden .
There lies the trick , controll counters passion, so try to be both .
Here is one I have just finished. plus a sketch that I did not use.