It’s a really good idea to clean up your trash cans now and then.  You can use bleach spray and wipe them down on the outside.  Fill with water and some bleach on the inside and let it sit for a while. 

Once your trash can is clean…get organized.  I buy a roll of trash bags for each can and throw it in the bottom of the trash can.  It doesn’t take up much space and they will always be right there for you to grab when you take out the trash.  It’s nice for a guest bathroom so people can dispose of what they need to without having to ask.