Slow Cooker makes a mess
The solution is real easy and you won't need do any of the crazy stuff mentioned above. Buy some baking paper (brown (sort of waxed) paper that you can line baking trays. The often come ready cut in baking tray sizes, which are plenty big enough. Fine the area that will be in the center of our crock pot when the lid is on. Take a sharp knife and cut an X shape in the center. Have someone, although, it can be done alone, gently pull the paper taut, not tight, and put the lid on your crock pot (with the X in the center) and gently press it down. You'll feel the paper seal the lid to the pot much better. Then as the steam rises through the paper it will condense on the lip and drip down onto the paper and will be funneled back into the pot by the X you cut in the center of the paper. Your problem will solved, for the price of baking paper. Best of luck and best of slow cooking without the mess.