I'll get the "is this still available" on Marketplace and I would reply with "Yes, when do you want to pick it up?" No response.
So now if I list on Marketplace I am sure to include that if the ad is up, the product is available so lets not do the "is this available" dance.
It's also common that someone will contact me on marketplace just so they can talk gear. Sometimes that's interesting and sometimes its the equivalent of the "golf guy who has all the golf equipment and clothes but is Senor Slice".