I like to repurpose all sorts of plastic containers, bottles, and jars. Often the original contents is covered by a paper, foil, or plastic seal. No matter how carefully I remove the seal, I sometimes have remnants of the seal stuck to the edges of the container.
I guess it's just scraping but I use one of those plastic pamper chef scrapers for things like that. I would guess the goo gone doesn't work well on the foil ones because it's harder for the goo gone to penetrate the foil to get to the glue. Soaking in hot water, scraping and then maybe goo gone any remaining stickiness is what I do. It can be surprisingly difficult, though.
99% of the time the glue is a thermal (hot-melt) glue that yields quite nicely to steam from your steam iron. Soften it with the steam and if necessary, scrape the rim with a butter knife (not a serrated knife).
Good idea. I just removed one but with sandpaper. It isn't what I had in mind as the edge is rough (I only had 80 grit).
The thermoplastic glue used to seal foil lids onto glass can be stubborn, but depending on the product can be taken off the rim of the glass with very little labor. Yo plait oui jars, for example, use glue that rapidly degrades in direct sunlight. After exposure, asoak in slightly acidic water such as rain (or tap water with a little vinegar) swells the glue and it becomes very easy to peel off or wipe off, it just floats off.