Sellable = legal
In general if you can buy it, than it equates to a legal routing. I have done it a few times since you also get the minimum 500 miles per segment. That can turn 1000 EQM flights into 2000 EQM flights.
The main drawbacks to those type of flights for me are:
1.) They are often on pinnacle CRJ's which in my book equates to riding Greyhound!! And I do NOT ride Greyhound (or pinnacle)
2.) There generally are not worldclubs at alot of the connecting points and/or focus cities. Ie. IND, Lexington etc.
These items probably are not major concerns for a lot of people, but they do factor into my decissions.