I noticed while on vacation that my DTRL will stay off if the parking brake is engaged even though the vehicle (01 Toyota Camry) is running. This tells me there is probably another way to disable them so they stay off while the vehicle is being used at least until the next start up.
The reason I'd like to do it is just to confuse people who are too nosey. Other than that I like my DTRL and feel they help make a vehicle more visible..