Best adhesive glues/paints are the ones made with powdered silver. I have some of the conductive silver paint. However if that stuff costs six bucks, doubt it is silver (the stuff I have costs a lot more!). This glue is probably carbon-based (black in color, rather than metallic). That means it'll have much higher resistance (carbon film is what resistors are made from). I guess if the metallic surface the glue is joining are physically close enough, the resistance will be small enough to be ignored.
But I agree with Chris. What advantage does it have over solder? Soldering is much quicker and results in a much better electrical and mechanical connection. Heat is not a problem if someone learns how to solder (it is not really difficult). I solder leads to tiny SMD 0402 LEDs (which are only 0.040" X 0.020") without burning them up.
There are applications in electronics where conductive glues or paints are the optimal solution, but IMO, it is not an optimal solution for DC decoder installs as a substitute for soldering.
