I opened a thread about scale a while back. I don't know if you read it. I bought about 40 plants from someone who was downsizing their greenhouse. They were infested!!!! I made up a plastic tub of malathion and dunked every plant. I let the media soak in the tub (in the pot) for about 5-10 minutes then baptised the foliage until I knew every nook and cranny was wet. Did it again a week or so later. I did use alcohol to wipe off what I could see, but that was just so I didn't see the dead ones. Haven't had a single one show up again. I feel this was easier than repotting and trying to wipe off all the leaves and for me it worked!