 You may want to give a good scrub to that grill before your Fourth of July barbecue. A British study says the average grill has 1.7 million bacteria microbes, making it dirtier than most toilet seats. Experts suggest a deep cleaning of your grill every five to seven uses. When was the last time you got sick from eating something that came off a grill? Ooh. I'll help you out. Never. Never.