Does a Private party have to disclose salvage title?

No, but it's very unethical! Plus, the buyer will find out when he goes to register it and may come over to your house and kick your ass. Is it worth it? Would you want someone to do that to you?

Now, if you were a buyer who unwittingly bought the car with a salvage title, sorry! Best to run the title number by the DMV before you buy so you know the title brand before you buy.