Why would real estate agent say he lists with 3 MLS's, & said others list with 1? I thought agents list w/ all?

ALL agents list with MLS's ONLY for which they pay the required fees. You need to ascertain with which MLS organizations any agent pays for. Frankly, I find it rather odd that any agent would pay for membership in three MLS organizations, since each one is rather pricey. Demand to see how this agent will list in three MLS organizations.