This is a general problem or I have a bad luck with customers 

LMAO
Nice one! No you aren’t wrong, it’s the nature of the beast.
Don’t want to generalize but the “picky” people tend to be females in charge of the project…i.e. “move this 1 pixel over, no move it back, no it looked better before” lol
All you can do is try to get better at recognizing these “picky” people before you take their money. I know sometimes it’s hard to turn money down but it’s better than 400+ emails of changes just to have them hand it over to someone else who really makes it look ugly!
Let them dig their own ditch because sometimes, they will call you back and admit they were wrong
Just had it happen the other day! Stay hopeful and cautious 
