Security wise one should always use multisig and real multisig. Real multisig makes sure the market cannot steal ur money, nor the seller.
You can detect you're dealing with real multisig if the address you need to deposit on starts with an 3 and you're provided with a 'redeemscript'.
If the market says it is multisig but you still need to deposit to an address starting with an one it is NOT multisig.
Find more about multisig here: https://www.youtube.com/watch?v=zIbUSaZBJgU https://www.youtube.com/watch?v=K-ccC9YZ8UI
At TOM: http://tom3j5jkjl7327oc.onion/docs/multisig-presentation.html
Its good to have trust but with Multisig you control!
Multisig cannot make sure about that, the market can steal the funds from escrow even with 'real' multisig implementation like the one on your market.