If you vigorously test a small inconspicuous patch with a solvent-dampened rag, you will be able to see straight away whether there is dissolved paint on the rag..
If you do use a strong solvent like petrol, work a bit of oil into exposed surfaces as you go – the solvent action seems to strip all oily residues from bare metal completely and rust starts to form on them with more-or-less immediate results, otherwise..