Incorrect exposure increases noise and thus affects perceived 'sharpness'. Exposing to the right also, from my testing over many years, is, in effect, often incorrectly exposing the image (or effectively parts of it to be more accurate), and depending on specifics can have a similar effect to incorrect exposure in that noise levels can marginally increase in some areas. I am an advocate in shooting 'within latitude' and this 'latitude' needs to be assessed for each camera - some have greater 'latitude' in terms of exposure than others. All that said, choice of apertures, movement (even with flash/strobe illumination at times) and precise point of focus are usually more significant.
Paul, underexposing does not in itself cause noise; only trying to correct that in postprocessing does (by amplifying shadow noise in underexposed areas). Maybe it's a semantic difference, but I feel it's an important one.
I am not sure what you mean about "shooting to the right incorrectly exposes an image". If you shoot to the right taking care to not blow out any highlights, you are maximally using (getting the highest possible signal to noise ratio from) your digital sensor. You can of course decrease the exposure in postprocessing a bit, without adding any noise.
In general, sharpness is not a function of exposure, within a wide range of reasonable parameters.