What's the best way to clean perf boards for reuse? To remove old solder and components?
Here's what I do when I decide to scrap a perf build and want to salvage some of the components and board:
Using braided copper wick, I desolder the "keepers," which are usually sockets or caps that happened to have a decent length of lead remaining.
Next, I clip the leads of all the remaining components where the they enter the holes on the top.
I can then rip off the spiderwebs of solder and leads from the bottom with needle-nose pliers. A number of the pads will pull off, but not too many if the original soldering was neat. If you want all the pads to be intact, then a long session of tedious desoldering is in order.
Finally, I use some 220 grit sandpaper to lightly shine up the pads that survived the process.
In general, pad-per-hole perboard is not re-usable. I have no idea about non-pad-per-hole.
For cleaning before soldering, heck, 3M scrub and water :-)