Mike - Speaking as someone with a chemistry background, it does take some effort to fake "dry old black wood", but the procedure is straightforward. The surface appearance of a 200+ antique is a combination of wear, dirt (soot, skin oils, tallow, beeswax, etc...) and - oxidation -.
This is the point I was trying make (though not very eloquently). Contrary to what the Keno's allude to in their book, and the antique collector's community seems to be convinced of, the "grunginess" of a surface, surface checking, and aging of the wood does NOT garantee that a piece is authentically old. Far from it, in fact, since the process by which a finish ages and the wood discolors is oxidation, and that oxidation can be greatly accelerated by elevating the oxygen content of the surrounding atmosphere and the temperature. This accelaration isn't linear - a 100% oxygen atmosphere will turn a fresh, green poplar board to the "nut brown" color often seen on the backs of colonial furniture in less than a week. It will do the same to eastern white pine, and vastly darken mahogany to the deep chocolate color seen on antiques. Cherry is even more responsive.
This same oxidation process can be combined with UV light exposure from a metal halide lamp to "alligator" a natural resin varnish finish, and do so very convincingly such that the finish under the brasses will be relatively untouched.
Finally, the end-grain checking on the bottoms of chair legs that the Kenos seem to be convinced is an indicator of authenticity, is relatively easily produced by alternating application of wetted fabric and a dry atmosphere.
My point here is that the grunginess, wear, oxidation and wood failure (checking) is fairly simple to produce, and all without resorting to dyes or stains that leave tell-tale indicators. This sort of treatment will even stand up to sophisticated (and expensive) micro-analysis with fluorescent dyes.
Knowing this means that authentication to high confidence can only be accomplished by researching a piece's history and method of construction, and even that is not 100%.
My conclusion is that there is no reason whatsoever to leave a period piece in a state of deriorated surface finish covered in grime. My personal opinion is that it's an insult to the artists that designed and constructed it.