If you place a value on your time: No.
Let's say you start with a $20 thrift store machine that looks like it's decent but average. You get it home, spend 2 hours cleaning it and checking it out, then spend another $10 on a belt and bobbin tire. At this point you have $30 invested not including gas or cleaning materials. You might be lucky to get $50 for the machine afterward. Yes, you made $20 at that point but how much effort did you put into it?
You can make some money sometimes if you luck into a machine that has a higher resale value than average but mostly people who flip machines do it because they love playing with them. It gives them a chance to mess with more machines than otherwise and maybe even cover some of the costs of their hobby.
As far as making money, you're better of working at McDonald's.
Rodney