I did a thing yesterday, and it worked out pretty well. I usually clean the exterior of my Dagne Dover Landon Carryalls with a lint roller or warm water and a soft cloth, but I noticed that the corners of the medium bag (the green one) had some grime, so I decided to cross my fingers and put it in the washing machine. Logically, I figured that if I could see dirt on the green one, the older black one (small Landon Carryall) had to be kinda dirty too, so I added it to the mix. They're neoprene, so I thought it wouldn't hurt.
I placed them both in a large net laundry bag, knotted the top of the bag, and threw it in with some other laundry. Cold water, regular amount of laundry soap.
They came out really well.
I left them in the bag and put them in the dryer with the rest of the laundry. Let them spin for about 20 minutes, removed them and allowed them to air dry. I worried about damaging the hardware (which is painted to match the bag), but it emerged unscathed, even though I heard the bags banging around as they tumbled dry (and the noise made me cringe). Next time, I would tie the net bag up into a clean, dry bed sheet before drying to further protect them from potential damage.
All in all, the experiment worked out! Both bags look good as new.
To anyone who owns a DD Landon Carryall or other neoprene bag, don't be afraid to wash it if it needs it.