I think it's pointless to try and pretend that everyone doesn't objectify other people at least sometimes and at least to a certain extent, or that recognising this makes you a terrible person. Go to a party, bar, club, beach or whatever and there will be some people of the appropriate sex you find drop-dead gorgeous, some you can maybe imagine gettin' wid under the right circumstances and some you find frankly unattractive (assuming you're neither asexual nor so undiscriminating that you'd happily screw pretty much anything with a pulse). Assigning numerical grades seems objectionable simply because it makes the whole thing that much more explicit.
(There's another problem I have with it, namely: how is the scale calibrated? Is it linear or logarithmic? Is a '10' only 1/9th more attractive than a '9', or twice, or ten times as attractive? Maybe it's an absolute scale, and a '10' represents a theoretically perfect beauty? Is a '5' defined as the population average?
I propose:
hotness quotient H = log10(P/A)
where
P = how much you'd like to shag the person in question
and
A = how much you'd like to shag the statistically average person of the appropriate sex
which is a relative scale in that it is automatically calibrated to your inherent background horniness. It has the advantage that it ranges from +inf to -inf and so can be used to grade anyone of arbitrary attractiveness or repulsiveness. 'Hot' people are +ve, 'unhot' people are -ve and someone who's exactly average rates as a 0.
The guy who does xkcd.com should do a cartoon about this - probably has done, in fact...)
