

I haven’t, but if you’re looking for the name, they’re called “wholesalers”. Typically they get houses that won’t sell on the market normally because they require too many fixes and aren’t safe to live in. They’re then sold to flippers.
Note, you don’t actually sell to wholesalers, you sign a contract with them to sell to the holder of the contract for the agreed upon price. Then the wholesaler sells the contract to the flipper for a flat fee.
2nd note, a lot of people think they’ll get cash once the contract is signed, that’s not the case as the wholesaler has to sell the contract. This can be adventageous if the owner is facing foreclosure. Typically you can get more money from a wholesaler/flipper, than if your house goes into foreclosure. Because the wholesaler usually has a list of flippers on the books and a sale is often just a call away.

Yea, most likely. Typically your options for getting out in order from best to worst are:
selling yourself
selling normally with a realtor
selling “as-is”/short sale normally with a realtor
burning the house down
these wholesale guys
foreclosure
though if the house is in decent shape the foreclosure can be better given the current state of the market.