Most “bad STL” complaints I see are a first-layer problem.

If the skirt isn’t sticking, stop the job. Clean the plate with dish soap, dry it, then run a 5-line skirt. If those lines look like spaghetti, you do not have a model problem — you have a z-offset or dirty-bed problem.

Bambu and Prusa hide this better than an Ender. Same physics.

I sell print-ready files and a separate 1-hour live session if the machine itself is the blocker. Files and repair are not the same product on purpose.