An email from reader D.M. in response to this post:

Don’t forget that DeMint ran into trouble on the national sales rax when he ran, and Jenkins (LA) and Coors (CO) may have lost their Senate races because of that issue (almost certainly in the case of Jenkins). I defend the sales tax as a theoretical construct, but it definitely is vulnerable to demagoguery.

I’d say it’s vulnerable to demagoguery and to accurate, devastating criticism.