Not all games you make are going to be a success unless you are simply perfect and no one is. One example of this for me is Battle Egg. The game was one of my worse flops after release. It didn't get sponsored for any money and made only $100 in ads over a year or so. When you work on a game for a long time it's important to step back and try look at it from a different point of view. Will others like what you just made? or is it only fun because YOU made it. This is a hard thing to get past, everything you do will always seem better to you then others because you know all the work behind it, you get emotionally attached so to speak, so it's best to try take a step back from that.
After a few months when you've cleared your head of the making of the game it's easier to judge. I made the art a little too messy and un-polished. The upgrade screen was way too simple and needed more upgrades and the UI was not nice to look at. The gameplay and idea I still thought was good but I badly executed it. The game was also too short. These mistakes are good reminders though to look at and learn from. I learn more from my mistakes more than I do from success usually. Designing is a tricky subject because you may think you are being unique and adding a ground breaking mechanic only to find most people don't like it even if it is new.
Overall don't get down about bad projects you release, just think of them as learning hurdles to get past.