Cleaning duct tape residue - options

Hi,

I want to clean some sticky residue, duct tape and eventually also blu-tac like putty.

I searched the web and this forum and some suggestions include:
olive oil (!)
rubbing alcohol (ethanol)
window-cleaning detergent
WD-40

I already tried the alcohol and it works but I still find myself scrubbing more than I would ideally like. Maybe there is no avoiding it.
Opinions on the window-cleaning products and WD-40?
Any chemistry experts want to chime in?

Olive oil to be honest I'd rather save for cooking, but if lots of you swear by it I can try as well :)