I saw ltcminer.io promoted by someone in a comment to a zerohedge post, and I decided to give it a try.

After spending about $60 worth of LTC, I was able to prove that it's a scam. Their website looks very professional, however, they lure you in to buy the next package above the one they promote as free, they pay if you withdraw small amounts below what you put in, and then all subsequent withdrawals stay as PENDING.

STAY AWAY from ltcminer.io!