ZookoZcash on Reddit suggested I post here. For users with more...private interests, perhaps this would be a good area to start promoting Zcash, as Bitcoin has already been a huge interest to people trading/exchanging adult/fetish/porn/etc. items that credit card companies have been hostile to.
I have made listings advertising discounts to buyers for using Zcash, but buyers could also offer to pay other sellers extra if they would accept Zcash. This could put it on the map in markets that are significant but aren't talked a lot about.
There are several adult markets on Reddit which largely trade in Bitcoin (some are temporarily being relaunched soon):
There are also chatrooms on Kik and Discord and elsewhere that I hope can be moved over to Riot which is very expertly distributed/federated, and supports e2e encryption and basic (but will be improved) video conferencing.