Used to frequent a new Goodwill store near my home...but the prices were too high....There is another huge store that has everything...good prices and a Senior Citizen day with 30 % off....I did ask one of the Clerks if they sprayed for bed bugs?...She said..."I'm sure they do"....
Even several Rental Centers here in my City have been sued by customers renting a mattress or sofa that had bed bugs....Aarons was sued 2 times...
I don't buy used furniture (mattress, sofas, chairs)...but metal stands or anything metal or iron seems safe....
And when I bought a new boxspring for my bed. I demanded them to enclose it on heavy-duty plastic, and they did (to be on the safe side).
Garage Sales/Estate Sales?...I ask for the item to be put into a plastic bag if it's made of cloth....and it's washed in hot water and dried at high heat...just in case....Been lucky so far.