Originally Posted by CliffordK

I'm not sure that is exactly true.

The newer Ultegra level hubs have exceptional labyrinth seals on their hubs. They also have much better quality cones than in the lower quality hubs.

Now, going the other way, you can get chains with hollow pins and slotted plates. Are those made to be cleaned?

Campagnolo may use high quality ceramic bearings in their Super Record bottom brackets, but the ones I've seen were without seals. So they spin very nicely, but get them contaminated, and they turn crunchy quickly.