take the scissors hold a lighter to them, keep flame on it until it catches fire, blow out the fire and inhale the smoke that comes off (scissor hash) repeat several times, then wipe the scissors with a cloth while they are still hot
I usually scrape what I can with a razor blade and smoke it. Then I have rather unconventional method of getting resin off things. Rub them with peanut butter, wipe it off with a paper towel, then wash with soap and water. I know it's weird, but peanut butter was how my mom got gum out of my hair and tree sap off my hands as a kid, and that's what I still use to deal with sticky today. ps - this is a great way to get resin or tar off of your hands and eliminate the smell in a hurry.
Soak in grain or rubbing alcohol, this will completely remove it, then allow the alcohol to evaporate, and enjoy your nice scissor hash. (If you have several plants to trim, bottle the alcohol/hash solution and wait to evaporate, until after harvesting the last plant, to save on solvent and make the run more worth-while)
If you just want clean scissors and you aren't concerned with keeping the scissor hash, I use a couple of q-tips and rubbing alcohol. Works like a charm.
I hear dipping them into cold water every so-often as you're trimming keeps them from getting sticky to begin with....but then no scissor hash...