That's a beautifully clear pic of the PCB, and I'd say the soldering looks pretty clean. It would be interesting if you could get an equally clear shot of the component side.
All those pins of the IC apparently shorting is extremely rare and would certainly account for all the screwy readings you were getting. I'm inclined to agree with Fletcher that either it failed very early due to a manufacturing defect, or possibly never worked correctly at all.
My method of removal is to use a pair of cutters like these to cut the legs tight against the body of the chip, I then (again like Fletcher) heat the legs individually at the solder joint, but use a pair of fine medical tweezers to pull the leg out.
It's then just a matter of careful use of a solder sucker and/or wick to clean up before putting a chip holder in.
It wasn't me!
(Well, actually, it probably was)