Regarding objective beauty, take the observer's bodily make-up (and perhaps some psychology details) and use that to make a subjective judgement unique to each observer upon each observed[1].
I'm not sure whether that should be "likes qualities that are similar to oneselve" or "likes qualities that are
dissimilar to oneself". On the one hand, there would be a certain amount of the former, after all dwarves like dwarf-shaped mates (as opposed to goblin-shaped ones), but on the other I could see a taste for the exotic.
Probably a mix of both, so a plump light-skinned dwarf might find an equally plump but exotically-dark potential partner quite attractive. To complicate matters, I could also imagine a preference of attraction for an equally-pasty but well-hewn opposite number, but I can see the former being reciprocated more than the latter (although I'm not sure if I have the relative reasoning sound on
that front!). Perhaps values that can nominally change (relative level of fitness, muscularity, hair-style, etc) are ones where overlapping qualities are the better attraction-enhancers, while intrinsics such as skin/eye-colours and the like are the features that are more sought for while being different.
Or have included into the dorf-DNA some hidden quality or other (e.g. a phermonic-like smell, an equivalent to whatever it is in humans that encourages different immunity genotypes to get get together) that enhances/deprecates whatever
other guides to beauty might exist.
With all the potential factors, it need not be necessarily certain that a partner who ticks all the boxes of one individual should find this given individual ticking all the boxes for
themselves! (IYSWIM.) When all this is said and done, should there be bad thoughts if a dorf's "perfect partner" pairs-up with someone else? Unrequited love? Love triangles? Love parallelograms? Cyclicly-mismatching love-parallelograms (
a la Midsummer Night's Dream)?
[1] Now I've got the tune "Music To Watch Girls By" with Andy Williams flitting 'round my head, only with
every instance of the word "Girls" or "Boys" substituted by "Dwarfs", thanks to my Pratchettesque outlook upon the nature of dwarves/dwarfs/dorfs.