Tourists are a stupid bunch. Tell them that they must visit Grinzing to experience Viennese Heurigers, and they will make sure to go to the very center of Grinzing and start from there. Place a Heuriger half a kilometer before the center of Grinzing and on a street parallel to the main one, and suddenly you have a tourist-free Heuriger. Which is a good thing, in general.
Muth must be quite nice in summer, when its garden is open. Inside it is a bit on a plain side and too bright to be cozy. It also does not seem to have a permanent menu (although there has been one on their website until recently), but the cook quite happily made me a Brettljause, so it makes sense to ask. Pity that he did not make a more filling one.
The Brettl itself was quite small and looked quite empty, the slices of ham, two different types of Speck and cheese, together with a glass of Grammelschmalz placed for aesthetic reasons rather than to create an impression of quantity. The meats and the Schmalz were unexpectedly tasty, the cheese was expectedly bland; and there was not much else worth writing about.
As a convenient tourist-less quick snack place for summer, Muth is great. They have plenty of wines to try, and Rheinriesling was very enjoyable (the Schankwein much less so). When one is hungry, however, one is better off looking elsewhere.