Pop-top cans that you can drink directly from are extremely convenient, but always be sure to (at least) wipe off the top of the can where you'll be putting your mouth. Think about it: most cans are stored in palettes that are transported in dirty trucks, stored in warehouses with insects and critters, and potentially handled by multiple people. This all adds up to lots of potential germs that you probably don't want inside your mouth. Clean the top!