Reusing Jars

My favorite salsa (Frog Ranch Medium) only has 40 mg sodium per 2 Tbsp serving. That's lower than any other at the grocery store, and probably lower than the recipes I have for home canning. And the ingredient list is short and natural (tomatoes, pickled peppers (peppers, vinegar, salt), onions, cilantro). Another bonus: it comes in a real, thick-walled Mason jar! We reuse those for drinking glasses and canning.
One problem remains: how to get the glue and bits of label off after washing the jar. I have a technique that works for me. First use water and a plastic scraper (I tend to hurt myself with metal) to get the paper off. A lot of sticky goo will remain. Get some cooking oil and rub it over the goo with your hands. DO NOT USE YOUR DISHWASHING SCRUBBIES- will ruin them. Use your hands, and rub pretty hard, like massaging the jar. When the oil clouds up, use undiluted dishwashing liquid to rub off the oil. Some of the goo will come off, but the rest will be transparent. Rinse off cloudy stuff with hot water. Apply more oil with a paper towel. Rub hard, and the remaining goo will come off. Then use dishwashing liquid again to remove the oil. Voila! New (tough) drinking glass or container for growing-time goodness!