There's another thread running on this exact model of 686. If you look nearby in this section you'll see it.
I have one of these in 4" that I carried as my duty gun for about 4-5 years. Now, because of that, maybe I don't have as high of expectations of the finish as a collector would, for example. I bought it specifically for duty, because I liked the look of blued guns, but the stainless seemed to make a lot of sense for a duty pistol. I'd grade my very-well-used one at about 90% with the backstrap being poorer - maybe 50-60% finish. I think the finish held up really well, considering I carried it daily on duty, practiced drawing every day, and in addition to shooting qualifications, shot it as my primary use revolver off-duty. I think the finish held up really well...
This is the revolver I shot two back-to-back perfect scores my first year at the Sheriff's Dept., as well as hitting a half-size body-shaped gong at 100 yards in the dark during "night qualifications" one spring. Also beat the pants off a buddy who thought there was no S&W that would shoot good enough to beat him with this revolver. Never had to pull the trigger with it, but it was out of the holster on some perps on a fair number of occasions.
So maybe my fond memories of this gun make me grade the finish a little higher... I wouldn't sell this revolver for any amount, regardless of condition-grading. Maybe I should get it out of the safe and take some pics, so everyone can see how the finish held up...