I can't describe any particular look, other than I know it when I see it. Same with personality, though I could probably nail that down to a degree if I wanted to analyse it properly.
Apart from that I generally I have something of a rough mental checklist I go through for more tangible things whenever I meet a potential partner. What goes through my mind is something like this (after passing initial visual inspection)
[Note: I generally rate these on something of a sliding scale from Acceptable to Blackmarks (stuff that will not result in immediate dismissal, but they will need to be good or outstanding match in other areas for me to allow this) to Instant dismissal (I just can't live with that, so it's goodbye)]
Age: should be about the same, too much younger or older and it's a bit weird, I am getting more flexible on this as I get older and age gaps dont seem quite as odd.
Height: Preferably shorter than me, same height Ok, taller is generally bad. A tiny bit taller might be acceptable if she makes up for it elsewhere, but waay taller and it's just no good, the black mark gets stronger for every inch taller than me.
Pets: no pets=good, cats/fish & other types of pets that aren't annoying=acceptable, dogs, birds & other exotic or weird pets = black mark (I particularly hate dogs for various reasons I wont go into here, so an extra black mark for dogs)
Misc Weird stuff: Not sure how to catergorise this, think of it like the 'man hands' episode of Seinfeld, just something odd or out of place that freaks me out, like arms hairier than mine or having a subtle but noticeable moustache, not a good look for a woman (yes I have encountered these, it's pretty much instant dismissal unless it's really minor).
Tattoos: Instand dismissal. I admit I have been wondering if I could deal with one of those tiny tattoos that are barely noticeable, but I really really dont like them (To clarify: I have no problem if other people like/want them, just dont blame me if I dont like it)
Piercings: Moderate piercings like ears are ok, the odd belly button or nose I can almost live with especially if she later grows out of it, but major amounts of, or just weird piercings are a big no no. I'll give a black mark as she can probably change this later, so it's not necessarily instant dismissal, but very close and a bit variable.
Wrong Opinions: Whilst I generally like an intelligent opinionated women and actually dont mind different opinions to my own, as long as they are backed up well enough. I do have to draw the line at people with extreme opinions one way or another or people not willing to listen to alternative opinions or points of view.
I think thats it.
When I look back over previous dates I do see some weird correlations, not in personality, but in appearence. eg First 3 girlfriends were all blondes, then a couple of brunettes, followed by 3x Asians, then the last two have been Indian or thereabouts. Unlike some people I have no real fetish or anything for any particular race or look, but I do seem to have grouped them together somewhat, which is strange. I'm wondering if this will continue or if it's just a weird coincidence.