Make a bundle with the cheesecloth and the pickling spices, placing pickling spices in a square of cheesecloth and tying it off with cotton string. Mix water, vinegar, ketchup, sugar, and onion powder in a large crock pot (the one I use is a 6-quart model). Add the bundle of pickling spices.
Put meat in fat side up in crock. Cook until meat is tender (low for 12 hours or high for 7-8 hours).
Remove spice bundle and throw away. Do not discard the juices nor turn off the crockpot. Take meat out and allow to cool.
Add 12 crumbled ginger snaps to juices that remain in the crockpot and allow to thicken.
Slice the meat and return to sauce in the crockpot.