It's hit and miss. Most of the time it's miss.
But I've bought a few things listed as "broken" or "for parts / repair" in the past, yet arrived with absolutely no issues, or very minor ones.
For example, I bought 3 USA Dreamcasts for $90 listed as "broken", but they all worked fine, other than all of them being yellow and one not reading discs (common issue - no biggie).
In a different case, I bought a "NEW 3DS XL" listed as broken, and the seller knew damn well what was wrong with it but yet feigned the typical ignorance saying things like "untested" or "I don't know what's wrong with it". Yet when I opened it, the liquid damage sticker was completely bled out, battery was completely swollen, and corrosion on some chips. It was cheap, but mentioning something like "hey, liquid was spilled on this" would've been at least informative.
I guess they didn't want to explain what happened to it and have the price be lowered.
If you like gambling and don't mind getting potentially scammed (item never being shipped and messages ignored, item being improperly described), go for it.
Buying and repairing is very risky, especially with disingenuous sellers.
Side note: Most Japanese sellers on Ebay have figured out that their items will still sell even if actually broken, so their prices will not be much fairer than ones from the US (assuming you're also in the US.)
Personally, I think having a Japanese console instead of the local region (assuming it isn't exclusive to Japan) devalues the price quite a bit.