I have dozens of Code 83 Streamline Insulfrog turnouts, some new, some retrieved from my second layout which I dismantled in 2012 (yikes, that long ago already?!?!?). I have never experienced shorting at the frogs, but I fully understand that sufficiently wide tire treads on even engine truck axles on a steamer, for example, could possibly bridge the two frog rails after they 'wye' away from the frog point AFTER the two tiny black plastic insulators. Never happened in my case, but... However, with "curved" turnouts and longer steamers that have a blind driver set to get around scale curves, you might find it a problem. I purchased several #7-5 curved Walthers/Shinohara turnouts seven years ago and found that some steamers shorted a that very point, where the frog rails diverged after the two little spacers. It was almost always only on the wider 'through' route where the blind driver, running inside the curve of the outer frog rail, swiped over the surface of the inner curved frog rail and caused a short.
I effected two remedies, with the preferred being using a cut-off disk and severing the inner frog rail just a bit further out from the plastic insulator. The idea is to sever it with two sets of spikehead details supporting the segment you isolate, not just one...or it'll move. The second method is widely used: use clear fingernail polish and paint the rails for about 3/8" outward down the divergence after the insulators. This will have to be repeated once every few months.
