Here's a lesson that I applied:
This picture is of a Fuller's Teasel (Dipsacus fullonum) that I shot near Wally World. Granted, it's nothing special, but to me it has a certain je ne sais quoi. I even tried to go artsy-fartsy with it and render it in black & white. It was then that I noted the "stink" factor: the ant on the top-right of teasel is distracting. I mean, it's a nice ant and all, but she wasn't meant to be the subject of my picture. She had to go.
Here is the artsy-fartsy black & white teasel but without the ant:
You probably think I'm talking about putting lipstick on a pig, if you want to call my teasel a pig. Truth be told, I'm thinking that the color shot is more aesthetically pleasing. But you have to admit that the shot is much better without the little photo bomber.