Can generic laptop ssd be put in a desktop, and is it bad to buy a used ssd?

Well i found a bunch of used laptop 128gb ssds for cheep on ebay for around $40. I want to see if i can buy a few of them and put them together in some type of Raid zero configuration. Since im low on money i was wondering if using laptop ssd's would be possible? (The generic type. The type people would pull out their laptop to sell)

A ssd out of a laptop is no different to any other ssd. Just be careful though, 2nd hand usually means no warranty and just read review of the models - read speeds etc. And avoid certain models - old kingston ssdnow's, old ocz's.
Also ask for ssdlife output screenshots - it will show its health and what not.

Yes and yes. You won't be able to determine how many read/write cycles the SSDs been through before you buy it.

If they're mSATA you would need an mSATA to SATA adapter card, but otherwise they'll fine.

I've got an mSATA SSD as the OS drive in "megaNAS".

Both of my crucial mx100's were pre-owned when I bought them. I wouldn't be scared of buying another pre-owned drive if its been taken care of.

i would just make sure that they were wiped ESPECIALLY IF THEY WERE BOUGHT OFF THE INTERNET