I’ve have mostly great luck with re-recording on used tapes. The key for me when buying them has been to make sure that they have been rewound back to the leader. I usually ask the seller to send me a picture of the tape with the door opened. I don’t tell them what I’m looking for. If I see the leader then, I usually have no problem. If I see tape, then I decline to buy. This works for pre-recorded tapes too. If a tape hasn’t been rewound for many, many years, it is often distorted and conformed to the shape where it makes contact with the tape guides. My experience has been that these usually have issues and often switch sides when recording. I’ve never successfully fixed a tape like that before.
The other trick that I do when recording with both new and used tapes is to fast forward and rewind them a few times before recording.
In addition, I always use a bulk tape eraser for 1 full minute, pause a while, and then erase once more for 1 minute. The eraser that I have was built for securely wiping big computer data reels so it’s more powerful than most.
Just my two cents worth. Hope that it might be useful.
David