I can't seem to find any reliable answer to this question. My understanding was always that PETG should be solvent-resistant, including to acetone, but parts printed from the various "PETG" filaments I have range from utterly falling apart (layer delaminations, outright ripping under tension) to deformation and smoothing of corners when soaked in acetone. Parts printed in actual PET are unaffected, as expected.
Is this an expected consequence of the modification to PET that produces PETG, or is it a sign that lots of filament vendors are deceptive and shipping some weird garbage and calling it "PETG"?