You can get a lot of the crap out with a hoover with the soft brush on the end (and the suction turned down, ideally, if you don't want to lose any keys
)
(We hot-desk at work and I think one of the women must have OCD, whichever desk she has to sit at requires her to clean it and the keyboard vigorously with the puffer and wet wipes before she starts.)(So I follow her round and sit at her clean desk next day!)