Although surface blur can be ok in Lab mode, I feel its best use there is for noise removal. In my opinion, catch-all techniques are rarely appropriate for skin retouching. Blur is always a last option for me, even in Lab mode. Suppose, for example, you were retouching a beauty closeup and needed to preserve pore texture. Blur would be terribly ineffective. Even if you aren't working on a closeup, I feel more specific and exact tools are almost always better ones. I have never encountered a photograph where I wanted to edit all areas of skin in the same way. Mind you, we're talking retouching, not applying "effects." If you find a photo that needs exactly the same retouch to all areas of skin, please let me know so I can cue the release of the flying pigs.