I don't like to use rubbing alcohol, not because it's ethyl alcohol but because it's usually 30% - 50% watere, and all that water can corrode parts and slows evaporation. It's easy to by isopropyl alcohol that's at least 90% pure.
Before thinking of unsoldering any switch, clean it out by spraying or pouring alcohol into the switch, then
press and release the key several times while it's upside down. You may want to do this over white paper to better see if any crud drips out. Repeat all this a few times.
Don't try soldering your keyboard until you first practice on some junked circuit boards. Boards with copper on just one side are easier to solder than double-sided boards with plated-through holes, and boards with at least 3-4 layers are even worse. Desoldering is even worse for multilayer boards. The safest way to desolder a key switch is by using a special solder called Chip Quik, which melts at a very low temperature. It's about $1 an inch, and you have to buy at least 12" - 18". The next best way to desolder is probably with 63% tin, 37% lead solder (60% tin, 40% lead is OK, too). Add some to each joint, then remove it with a solder sucker or copper desoldering braid. Brush-on rosin flux can help the braid work much better. If at first you don't succeed, add solder again and repeat the whole process, rather than try only the solder sucker or braid again. You'll do less heat damage with a soldering iron rated for too much power than too little, and for single-layer boards you probably want 35W - 40W, for double layer 40W - 50W, and for more than 2 layers, probably 50W - 60W. You must clean the soldering tip frequently during use or it won't conduct heat well at all. Also 50W - 60W can do damage if the soldering iron isn't temperature regulated. When installing key switches, be sure they mount completely flush against the circuit board or the solder joints will crack from stress.
