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Keep the alcohol away from the paint finish. It acts as a solvent. Enough of it will start pulling up paint. Especially if it's in an area that doesn't have a ton of coverage like around seals and seams.
Pretty much all paint cleaners, thinners and solvents are alcohol based. Lacquer thinner, MEK etc. Prolonged contact is meant to dissolve the paint chemicals, so never clean painted surfaces with it.
On the inner seams and seal areas I use either a mild detergent or simply warm water and a micro-fiber towl. As a rule of thumb, if I didn't buy it at least from the auto-care isle at my local auto store, it doesn't touch my cars.
On our C5, the black paint inside the hatch was so fragile that some accidental overspray of windex while cleaning the glass, left very obvious marks that never could be removed.
On the C6, I've been using GM Glass Cleaner (the white foamy stuff in the spray can) to clean the glass and also the black paint, that seems to work ok. Finish off with just a damp rag on the paint.
Sorry about your damage, it's appalling that GM doesn't either use better paint or at least warn the owners.