I think you mean money' laundering. I guess if you laundered the drugs they'd not be any use ;)
I'm a full time resident in Mexico. As soon as you get away from the border, Mexican pesos are the only acceptable currency. A few stores will
accept US dollars but, as the other poster indicated, they are reluctant to take too much due to the Mexican money laundering laws and the charges that banks make to accept US dollars.
I'd be careful about using NOB credit and debit cards at Pemex stations. They have the same scams here as NOB. e.g readers on the machines , etc.