Humm, I would NOT worry about looking differently! There are plenty of Mexicans who do NOT like Indians!
This said, I am afraid that many here who are not that familiar with the current situation in Mexico. A lot of news is targeting the border zone with the United States, but the current center of violence has changed. Simply stated the entire coast from Sonora through Chiapas has a great number of hot zones with Acapulco and Lazaro Cardenas being the worst of all. Areas to the south --think Jalisco, Michoacán, Oaxaca, and Chiapas-- are not immune to danger. For instance, the road between Oaxaca and Huatulco is a dangerous one that is often controlled by corrupt soldiers or militants. Currently, the corrupt teachers’ unions are creating a lot of havoc in Oaxaca. http://www.excelsior.com.mx/nacional/2015/06/03/1027418
All in all, while a stay in Oaxaca (as in the city) might be OK, it’s best to fly directly and NOT venture too far away from the major city.
By the way, Oaxaca is not part of Central Mexico!