XMRWhere the Monero actually gets spent
A Monero-only market is one that took the second coin away on purpose. No Bitcoin door, no swap in the back. That sounds like less until you understand what the second door was for.
Most markets accept both Bitcoin and Monero and call it choice. In practice the Bitcoin option is the leak, because everything paid through it lands on a public ledger. A Monero-only market removes that door entirely. From a buyer's side nothing useful is missing, since Monero is the coin you wanted anyway, and the trap under the cheaper-looking option is simply gone. Single-coin is not a market cutting corners. It is a market taking a side.
What to look for in one
Judge a Monero-only market on a few plain things. Escrow that holds your payment until you confirm the order arrived, ideally 2 of 3 multisig so no single party can move the coin alone. More than one onion link kept live, so a flood or a downed node does not lock you out. An anti-phishing check on the login that lets you confirm you are on the real market. And a dispute process that actually resolves. The rest is presentation.
BlackOps is the market we send people to. It settles in Monero and nothing else, runs multisig escrow, and keeps several onion links warm for uptime. Copy a verified link, open it in Tor Browser, and confirm the address against the login screen before you sign in.
blackops5l63qnwnmlnsfvtlu66md3x3vp3fdtpna42eq7ozujr67hid.onionblackops6kignp3eddmvqcfkjzf6qr6haxbmkypc2xtqlnhuu4ak4dqd.onionblackops27m32abqvbhnyswgazqawxqbznbzkkkv5sjo7gve2ndpsdad.onionReaching it safely
BlackOps has no clearnet address, so anything on the normal web using its name is a copy. Take a link from the block above, never type an onion by hand, and when the login loads read the address on the page back against your bar. The real market prints its onion in the anti-phishing image and again in the header, and a clone cannot fake both while sending you elsewhere. The full run-through is on the next page.