The minute amount of dirt build up will not cause a problem, plus you can potentially do more harm than good by taking the throttle body apart. If you are getting a large amount of dirt build up then your air filter is not filtering properly or your engine internals (valves and valve guides, or pistons and rings) are worn.
mmm not sure but think the Z throws back quite a lot of oil after hefty revving (inspired driving) Installed an Oil catch can a while back to catch anything going into the plenum chamber itself. Looking at getting one for the intake side also since my Z seem to suffer a bit from this. Did a compression test and got 12.5 on all cylinders bar one that shown 12...so all good there. The filter is cleaning as it should so not worried there.