Cleaning rubber goo

That depends on what the substrate is. If possible, I use lacquer thinner, which is a very powerful solvent. For example, it removes label adhesive or rubber cement faster than anything else I've tried. But if the substrate is some kind of plastic, it probably objects to this, so something less potent (and less effective) is needed. A label chemist told me that label adhesive residue can be removed, slowly but safely, with WD-40. I haven't tried that on former rubber, but it might serve for that as well. The key point is that most plastics don't mind WD-40. If it matters a lot, test the proposed solvent first on an inconspicuous/noncritical part of the substrate. Sometimes you get surprised. For example, ethanol is safe for nearly all plastics, but it badly messes up clear acrylic ("plexiglas"). paul