This issue happens can you import CAD files and drape them. It's always been a bug and it lingers still. I would recommend using EdgeTools and clean up any little bits and shards in your CAD file. Then you can try also running it on your topo after draping. This doesnt always work but it gets a good amount of unclean cuts. You can also bet that arcs tend to have this issue when draping. To find the culprit, I turn on hidden and start painting my areas, you will eventually find where the bleeder is and fix the teeny-tiny edge that did not cut cleanly.
Also try Fredo's Edge Inspector.