The three/ten/180 second rule is hotly debated. Just how long can food sit on the ground before you eat it? According to the doctors it’s not a long time (if you’re worried about bacteria transfering from surface to surface). But who listens to doctors anyway.
Here’s a handy flow chart that’ll help you know when to hold it, know when to fold it, know when to walk away and know when to run. I found it here.