I've never eaten a mouthful of sand, but if I did, I can't imagine it would taste much different than the rice and beans served at Tacos Del Mar.
If it is the goal of TDM to produce the most bland tasting Mexican food on the planet, they are doing a pretty good job.
In addition to the rice and beans, not much can be said for their dry, flavor-free steak as well. If you're into eating cardboard, I suggest you try TDM's steak tacos. You'll be in heaven.
I'd give the place one star if it weren't for the friendly employees. Those bastards.