That black grease really stains. I have a sweat shirt that got some on it when I pulled the transaxle for my clutch job. This was back in December and the shirt has been washed many times. Guess what, the grease marks are still there.
Another thing to keep in mind is that the greases may be incompatible. Of course you probably don't know what the old grease is, so you have to wash off the old CV joints and then repack. Don't ask me why this is true but all the applicable greases have this warning printed on them.