People are making comments about cheap bearings failing early, but IMO this isn't the problem, since cheap bearings can last bloody ages.

The problem is the preload often isn't properly set and/or locked on cheap stuff, and this is what destroys bearings, far quicker than normal wear on cheap parts.

Anytime you buy anything cheap with adjustable bearings, you should check the preload. People worry about lube, but preload is way more important.

In fact, make that anytime you acquire anything with adjustable bearings you should check the preload; you can usually improve on it.

Parts like pedals and hubs have to be super-crappy to be unfit for purpose (regardless of setup), but I'd say I'm seeing it more these days on the very cheapest stuff...