There's been discussion on RPGnet about the Comeliness attribute added in Unearthed Arcana (AD&D1e.) I thought I'd talk a bit about my attitude when it first came out versus how I'd handle Comeliness now.
When I first read UA, I was pretty receptive, although not completely enthralled, by its contents. I was pro-Comeliness, and since I noticed that Comeliness was modified by both Charisma and Constitution, I worked out four additional attributes for Charisma paired with each of the four remaining attributes: Physique (Strength,) Grace (Dex,) Voice (Int,) and Manners (Wis.) I still have my notes on the class and racial adjustments.
That's not the way I'd do it now. It's easier to use something like labels to mark physical attractiveness, particularly with multiple standards of beauty. "Attractive to Elves" would add a bonus in situations where it mattered, but a penalty when dealing with NPCs who find the elven standards of beauty revolting, and a penalty when rolling a reaction for a possible kidnapper, and a penalty when dealing with a jealous elf-woman.
One issue with Comeliness raised in the thread has been the ongoing debate about personality mechanics. Should a player character be forced to role-play attraction to a high Comeliness NPC? My solution is not to take over a PC or penalize them for failure to role-play, but to dangle a carrot: if you choose, you can declare that your character is in love and can add the attractiveness bonuses of the target of your affection as bonuses to actions when rescuing, protecting, or merely trying to get close to the object of your desire. This means that the more attractive (mechanically) the NPC, the more likely the player will choose to role-play being in love, merely because of the benefits.
It's more or less one of the mechanics I suggested for Sanity. Interpret that statement however you will.