Coolant pipes where they enter engine.

[Gnasher]

@Gnasher, is there any reason why owners could not coat the bottom of these pipe galleries with grease? As it would both protect the bottoms of the pipes and all the crap that goes in there would stick to the grease etc..

You could, providing it was heat resistant enough. That said any grease/oil would act as a grit/muck trap ie stuff would stick to it.  Just regular flushing with clean water will help prevent major issues.  Its the same with most sparkplug wells grit and muck will get in there and eventhough they have drain holes to allow water to escape grit/muck can't. Periodic flushing/air blasting is the way to go, especially before removing the plugs.