Got my first table this past May and I can totally relate to this. Some nights it all feels good and playing is very enjoyable. Other nights - not so much. One of the things my wife keeps saying as I try to coax her downstairs to play is "I suck". Whenever she says it, I respond by saying that everyone who plays on our table sucks in a relative sense and that everyone has bad games and puts up bad scores.
Sometimes, if I feel that it is just "one of those nights", I just walk away from the table and stop the madness.
Funny side story. The day I got my table, I took a few buddies along to load and unload it. When we got to my house and had it set up, one of them kind of refused to play as we gave it a few spins. When we asked why, Ryan said that he had never been good at pinball and that the ball always just drained straight don the middle on every ball whenever he played. We chirped at him relentlessly until he finally agreed to play a game. All five balls went SDTM. Honestly, they did. Never saw anything like it in my life. I think he's cursed...