The mention of Watson's opinion on Holmes's facial hair had been a throwaway statement at first. Holmes generally dislikes feeling so disheveled as to go unshaven for too long, always has, and so gives little thought to his unshaven state beyond the fact that it bothers him slightly. But perhaps Watson might like it; that is something worth investigating.

"You cannot complain?" he returns, playfully. "What am I to glean from that? Am I only moderately repulsive, but not so much as to detract from my appeal too seriously?"

This is nice; calming and quiet and nice. He makes sure Watson's shirt is pushed away as much as possible, and he dutifully sets to tracing his initials against Watson's chest, over his heart.