I hate that feeling! I thought i was OCD about cleaning too and then i got 2 infections in a row - almost stopped brewing.
Then i got quite a large container filled with water and star san and percarbonate and left my siphoning wand, unused spigots, bottling wand, etc soaking in it the whole time i'm not using them - Buckets get soaked in percarbonate after use then sprayed with star san..i spray that star san on everything all the time. No infection since.
But hey I'm pretty sure i just jinxed my self - i'll expect an infection soon
Secondarys i believe are the reasons i got my infections tho.. all that airspace in the fermenter with no fermenting really going on...just potential nasties looking for unfermentable sugars