The slow speed of cassette tape is the main reason they don't perform well in the high frequencies. I have seen many that were exceptional (meaning, they could record/play the range of human hearing or better at -20dB VU, but none couold do it at 0VU. One issue with VHS is the way the tape path stresses the bottom edge of the tape, which happens to be where the synch signal is recorded and needs to be constant. If it has stretched too much, dropouts and tearing of the image occurs. I would assume it messes up the HiFi audio since that's encoded by the video head drum.