but I don't understand how can they be rented out if no one seem to be "mining" at their facility yet? I think I would be less worried once I see more physical proof
This is not definitive proof per se, but someone/something is mining litecoinpool (I estimate about 190 L3+'s):
https://www.litecoinpool.org/stats#2
gigawatt
95,273 MH/s
46.7 LTC/d