I am in Oaxaca city and I have to say the food is better than I could have ever imagined. Even the crappiest places have better food than at any "Mexican" places I have found in the US. I did eat at one tourist place on the Zocalo that wasnt great, but I should have known better.
And right now, there is both a coffee fair and a Mezcal fair offering tastings of local products. The coffee fair is free but the Mezcal fair costs a whole buck to get in and taste all the Mezcal you can before you fall over.
Come on down!