If you take care of your goggles, they take care of you. But it doesn't take much to damage a set of goggles so they become ineffective.
When it comes to goggle care, most notably the first thing we usually mess up is the lens. We either scratch them, or somehow make them so they tend to fog up with little effort. So what can we do to keep them new and functional?
First, according to Randy Nagel of Pro-Vue, only use a soft cloth and water to clean them. They're not glass, so don't use glass cleaners, which usually have some sort of alcohol base. They're made of lexan. Nagel says that cleaning solutions have a tendency to crack the lexan. So just use water.
Also, most snowmobile goggles are dual-pane. Nagel says the inner lens of a dual-pane goggle is made from butyrate, a soft absorbent plastic. Butyrate is actually designed to absorb some of the moisture that causes the goggles to fog. However, if you get the lens too wet it will saturate, making it difficult to see through.
Nagel warns against trying to clean the inside of a dual-lens goggle. "Since Butyrate is soft, you're very likely to scratch it if you try to clean it. It's best to just leave the inside part of the lens alone."
Another idea for maintaining the goggle frame is to wash the foam. Nagel explains that sweat will cause the foam to break down. However, if you remove the lens, you can easily hand-wash the foam and extend its life.