You will be the next guy’s last guy.

Suppose you live in a really old house and that you are an idiot. But that’s redundant, because what you are trying to do a lot of times is in direct conflict with the laws of thermodynamics. Entropy always increases, which means your house is actually required by law to fall down. And the last guy pretty much buggered up every aspect of repair and maintenance he executed. Here’s a hint: That last guy can be your best excuse. When you perform a particularly egregious kludge, enough thick drippy coats of paint can make your crappy new work look old.