A huge percentage never return your phone calls to begin with - hey genius, I'm trying to give you business. Money which you can use to buy things. A huge percentage never start or complete the job on time, always over promising, always some bullshit issue with "waiting for my supplier to get more in... I hope to get it finished by next week" and "oh, that's extra, my quote didn't include the such-and-such". Drives me fucking crazy.