If you're ready for a serious adhesive battle, then head to the auto store. There are plenty of commercial products, such as Fast Orange or Goo Gone, that can give you a leg up. Designed for cleaning motor oil and grease from hands, they work just as well for sticker, tape and glue residue. Why? They contain a degreasing agent. In the case of citrus cleaners like Fast Orange, the degreasing agent is usually d-Limonene. Others rely on heptanes, a powerful solvent. To be safe, both types of products should be used in small measure in a well-ventilated area.
WD-40 is a standby in many households because a shot of this lubricant can fix everything from squeaky hinges to frozen door locks. Although the product's 1950s origins were in rust prevention, we like WD-40 for its ability to cut through sticky residue on glass. Spray it on, let it sit and use a clean cloth to remove. And, if you'd like to impress your friends not only with your adhesive removing skills, but also with your trivia knowledge, try this on for size: WD-40 is short for Water Displacement, 40th Attempt -- the name a chemist gave it during development.
Why do these oily products work so well on sticky goo? If you hearken back to chemistry 101, you'll recall most adhesives -- at least the kind we've got gumming up our glass -- are oil-soluble. So it only makes sense a bit of greasy fluid will shorten their life spans. And if you need to remove adhesive from other colored glass items, such as beer bottles or bud vases, it will work just as well.
Of course, you could go an entirely different direction by using lighter fluid. Its active ingredient, naptha, will make short work of any stickiness. For an equally serious approach, soak a cloth in denatured alcohol and apply it to the adhesive. Just be sure you have plenty of ventilation and aren't near an open flame.