Try a flat-tipped screwdriver, too. Sometimes a gentle nudge or two will pop glue off the rail tops. So, too, would be a sharp hobby blade or a carpet knife/box cutter.
Sandpaper would be my last step (not a last resort, a last step) after wetting the glue, depending on its type, and trying to scrape or wipe it up when it was softened.
I do use 600 grit to clean between the points rail blades' inner surfaces and the stock rail when turnouts become intermittent and engines begin to stall or hesitate. Sometimes I lift the black crud that accumulates near joints where there might be arcing/sparking, or it happens near the insulators at insulfrog frog rails.
-Crandell