Joyce Slaton of Chow tracked me down the other day and we had a lovely chat about yucky things after I had taken my daughter to school and before she had to pick up her daughter. Time zones.

Slaton writes that research conducted in the summer of 2011 by Harris Interactive found a solid 79 percent of respondents saying they'd avoid a restaurant after encountering a nasty bathroom. But does the link between a filthy toilet and a dirty prep table even make sense? Hard data is rare. Though health and restaurant inspectors do check for the general appearance of cleanliness in restrooms and dining areas, they save their swabs and scientific gauges for the food-prep areas.

But as Douglas Powell, professor of food safety at Kansas State University, publisher of food safety-focused barfblog.com, and a passionate proponent of proper handwashing (we'll get to that in a moment), says, "There's a yuck factor when you go in and say, 'Eww, this is dirty, what else is?' But there's no proven correlation between having a dirty bathroom and unsafe food. The employees have different sinks to wash their hands in. You don't see those—they're at the back."

Chowhound poster soupkitten makes a good point in a thread titled Freezing Bathrooms=Omen: "Folks who want to point to a smudge on the front window of a restaurant or a smudge on the floor of the men's room as evidence that the kitchen of a restaurant or any other business is unsanitary seriously need to realize that most establishments have divisions of labor and that the brunch crew comes in at 6 a.m. to crack eggs, not wash windows and wipe down toilet seats!"

Meanwhile, Powell (politely) pshaw-ed my notion that a dirty bathroom meant that diners should order differently or avoid a restaurant.

"But," he warns, "if you see a cook or a waiter come in and use the bathroom and start to leave without washing up, say something [like], 'Dude, wash your hands!'" Powell also hopes patrons will speak up when bathrooms don't have the tools for proper handwashing. Which are?

• Vigorously flowing water: "Temperature doesn't matter," says Powell, despite the fact that we've all been told that warm water works better. Microbiologically, it doesn't matter.

• Soap: Lather energetically for 10 seconds, not 20 as you may have heard. It's OK with Powell if you want to sing "Happy Birthday" to yourself while you do it, but he'd rather you count than sing kiddie songs.

• Paper towels: The blow-dryers disperse microorganisms into the air and they don't get your hands dry, says Dr. Powell. Paper towels are better. But don't bother using one to hold the bathroom door handle as you go out: The door handle surface isn't a particularly great place for bacteria to grow.