Nothing special about the rads that I'm aware of. Just had mine out a couple of weeks ago to seal up a leak in the side tank. Took the garden hose to the bottom hose port on the rad and flushed it out for good measure.
No reason you can't just pull it out and try that yourself. If you get a lot of crap coming out of it then you know you've got a problem. Also should be able to tell if it's clogged if you can't run any water all the way through it.
Cosmos Black/Black 1995 540iA M-Sport
BMW Individual Exclusive Edition, 1 of 65 total, 9/25/95 Build