You know the type of thing - the Craft Fair just isn't going your way. The lady next door makes hideous necklaces but everyone loves them and rushes past your stall to hand over their money to her. The cupcakes sell out, and you have people asking you 'Did you make this?' It can be a real downer and sap your inspiration - you wonder why you create anything at all 
Wait a minute. Take a breath. Firstly, try not to let the necklace lady bother you - I know it's tough I've been there, questioned my inspiration and my ideas. The fault, however, might not be yours. It might be the demographics of the area (e.g. how much money earned, types of houses, types of schools etc.,). It may just be the wrong sort of fair that we have to put down to experience.
I know that my pins don't sell at places like school fairs, people expect things to be much cheaper. I realised that I have to limit myself to fairs where the outlay for a stall is not too high, and the standard of sellers is of the similar or higher prices or a large fair with a huge range of items for sale where I take my chances like everyone else. Different fairs for different folks!
It takes me time to bounce back after a bad fair. I have recognised that my handmade pins don't rock everyone's boat and take a deep breath, acknowledging that the hideous junk sold by Mr X next door may just be the next big thing, and that the next fair I do might well be my best yet, and this one is his party.
After a bad fair - do something to cheer yourself up. Do something you want to - read your favourite book, knit, meet friends, whatever, just don't be negative. Don't beat yourself up about how bad your things are, the chances are they just didn't fit in with the craft fair - it happens, and when it does .... Lift up your head and look to the next fair, keep your spirits up - you know your stuff is good, and you love making it. Like Dory says in 'Finding Nemo "Just keep swimming, Just keep swimming!!" Your time will come!
Marjorie (Whskr) is well known as a maker of Art Dolls & Copper Curiosities - unique copper pins. If you enjoy the article, please give it the Green Thumb of Praise!