I recently received some older lures, and several of the plastic ones have a white, soapy residue on them. One was completely covered, the others just had some here and there. I soaked them in warm water and dish detergent and the ones that only had a little bit of this stuff came clean with a good scrubbing. The one that was covered looks much better after a good scrubbing too, but it still has some of this stuff that doesn't want to come off. Does anyone know what causes this stuff to form in the first place or, more importantly, a good way to get rid of the rest of it?

I had the same things on some of my grandfather's lures  he gave me.

I just scrubbed until it came off.

Seemed like some type of mildew/mold to me.  Try a gentle bathroom cleaner designed for those conditions.

You boys need to stop playing with your lures in the bath tub....    ;D

All my old trust Bombers do this.

Like SPEED said, just gently scrub off. I use plain water and an old toothbrush, (or one of your buddies if he outfishes you). Must be the plastic used.

I have used Gel-Gloss, atile and bath polishing / waxing product with great results. Works good on rods/reels too....

Best lure cleaner on the planet is the Miracle Cloth. They are amazing on plastic and wood lures and take that white scum right off. The lures look like new after using the cloth.

Here is a link to a bunch of them on eBay.

Not me selling them, its just where I get mine.

http://sporting-goods.shop.ebay.com/Outdoor-Sports-/159043/i.html?_nkw=miracle+cloth&_catref=1&_fln=1&_trksid=p3286.c0.m282

that miracle cloth looks/sounds pretty impressive...

so much so that i just bought one... lol!!