It looks like most of those "accept Bitcoin" by using a service like Bitpay. In other words, they accept only fiat currencies but allow you to send them payments through another service that will exchange Bitcoin for some fiat currency.

You can trade sexual favors for all kinds of stuff, but it doesn't make it currency.

BitPay doesn't coun't. The merchants are all accepting whatever currency BitPay converts into.

I'll sell you my car for a sack of turds, assuming someone will exchange it for $15K and hand me the cash first.