The electrons don't care what it looks like, they just need to get to the right places, and not the wrong ones, at the right time. If it currently works, rescue by careful cleaning and cleaning damage restoration is likely, if not, it is a gamble. If you have not tried powering it up yet, it is best to clean and restore it first, if you are willing to invest the effort on faith, to avoid creating any additional whisker shorts by powering up crap. Interestingly enough, it may work better electrically without the pads, so long as the trace just runs up to the plated thru hole and connects to the IC leadframe, and corrosion crap does not shunt out the signals to wrong places. Only you can decide if the stuff below is worth the hassle.
A good first step in assessment is to have a reference. This may be an IDENTICAL revision of the PC board, or good closeup photos of the topside taken with a tripod. This reference is only needed when in the next step a trace vanishes and you need to put it back! It's handy to be able to annotate the reference with a magic marker during the following step.
Next you need to be brave and clean off the crap. I'm sure different readers have their own favorite methods, and the last time I wrote about this I got crap from down under. So I am just going to say you need to gently remove the crap with tap water and only if necessary with gentle rubbing. Perhaps the most difficult thing here is deciding whether underneath any part needs special attention, and a good stereomicroscope or handheld 10x/20x magnifier will help with this inspection step. If the liquid surrounds an IC and you see green going beneath it perhaps a device like an oral irrigator can blast the stuff loose saving you from trying to floss your IC's! As you wash, if you see a trace crumbling away, mark it on your reference, because if by the time you finish cleaning it is completely gone, your mark may be the only reminder you need to put something back!
The final rinse may be distilled water if you want to avoid water spots, but this board is never going to be pretty. Shake and blot dry, then inspect with 20X magnification. Repair broken connections with tiny insulated wire jumpers and resolder questionable soldered connections. Allow several days to dry, one drop of water under a surface mount flush device evaporates only along the very edges and takes a long time. Regarding both washing and later heating to speed drying, it's best not to heat the board any hotter than you can stand with your hand. If you are the systematic, patient type, wait several days after washing to do any soldering, because the water that gets under the traces and pads has a way of flashing into steam and lifting copper when hit by the soldering iron. If you gotta have action now be prepared to stick down a few with superglue or 5 minute epoxy. There is a hovering technique with the iron where you pre-dry a connection area before touching it and almost instantaneously slamming it to molten solder temperature. In any case the board better be clean and dry when you power it up for testing, or little metal whiskers will eventually grow and create some additional traces in places you can't see or get to, and all your work will be for nothing...
