Well, sometimes your keyboard is a bit too dirty to be usable, luckily for us this website has some tips to offer when trying to clean your keyboard.
Use an air compressor
Use isopropyl alcohol
Use a USB vacuum cleaner
Remove all of the keys
Clorox Wipes or household disinfectants
Use the dishwasher
Use Post-it Notes
Use a hairdryer
Use Scotch Tape
Get rid of the mysterious sticky stuff under your keyboard with compressed air equipped with an extension nozzle. Turn the can at a 45-degree angle and spray between the keys. Tap and shake the keyboard and then repeat spraying. Finish by cleaning the piled up grime with a damp cloth.
I actually have an air blower so it's not a big issue for me but for some one who doesn't have that luxury you can check out the site and find yourself a nice cleaning solution.