Cash house buying companies are a great way to get rid of your house quickly and without hassle. However, there are some companies that are not legitimate and you should be careful when dealing with them.
The first thing you should do is to make sure that the company is registered with the state. You can do this by checking their website or by calling them up. If they don't have a website, it's probably not a good sign.
You should also read the contract carefully before signing it. Make sure that you understand everything in it and watch out for "escape clauses". These are clauses in the contract that allow the company to back out of their agreement for any given reason. It's usually because they couldn't find another third-party to sell your home to at a higher price, so they will come back to you to try to renegotiate the price or use their "escape clause" to get out of the contract.