Frits can be cleaned using an ultrasonic bath with soapy water or ethanol, depending on what particles and gunk is stuck in it.
Pressurized steam and power washing nozzles can be used for really tough encrustations of water based materials, and even hot soapy pressurized water can be used for non-polar removal.
CLR remover is an excellent cleaner for removal of calcium and rust deposits from hard water in condensers and such.
Reactions that are sensitive to water, such as using organometallic catalysts, must be performed in thoroughly dehydrated glassware. The glass should be placed under vacuum on a Schlenck manifold, and heated with a torch to burn off the internal monolayer of water chemisorbed (hydrating) the glassware. Then the Schlenck should be used to fill the flask with dry N2. After fire drying, perform chemical operations in a desiccated glove box in case of small leaks.