I was able to 'fix' my MBP without buying a replacement part or taking it to the Genius Bar. After spilling several large drops of juice along the top of the trackpad, the cursor would randomly move, swipe and click in OSX as if someone was using it. Out of warranty, I ended up disabling the trackpad through Terminal and used an external mouse to make my MBP usable again. Here's how I ended up solving this on the cheap -
First, I followed Simran's guide to remove the trackpad from the chassis. I cleaned the bottom of the trackpad with rubbing alcohol pads till every bit of sticky residue was removed. That didn't fix the issue, though. What you really need to clean is this -
- the data cable (see above) and the ZIF connector where it meets the trackpad. Any liquid slipping through the top portion of the trackpad could land directly on the exposed portion of the cable and make its way down to the ZIF connector. That's likely where the short was happening. I scrubbed both areas with a cotton swab and cotton ball soaked in rubbing alcohol several times. Be careful not to damage the cable.
After reassembly, the trackpad felt as good as new. I saved myself the hundreds it would've cost at the Genius Bar and the $100 or so the trackpad and cable would cost to replace. Not too shabby.