I, like others in the thread, am always washing my hands, so it's isn't exclusive to right before a gaming session. When it comes to gaming, I don't eat and touch things. I'll have a beverage with me, but I don't handle food items, pick up the controller and repeat. If I have to have a snack, I wash before and after.
I remember back in the SNES days...A friend and I were sharing a bag of pretzels, I noticed he started rubbing his fingers all over his greasy nose and face, place his hand in the bag, eat the snack and handle the controller. I stopped eating the snacks. He then dug out stuck pretzel outta his teeth, place his hand in the bag and go right back to gaming. He was a good guy, but oblivious to how his personal hygiene affected our gaming time.