ThreeCorners,

An outstanding horse will exhibit superior conformation and a quality horse has more attractiveness and eye appeal. So, if we are talking about a phenotypically outstanding horse, then it is going to tend to be "pretty".

My knowledge of phenotype is that it is just the outward physical manifestation of an organism - anything that is part of the observable structure, function or behavior of it. Phenotype does not imply proper form to function, nor prettiness. The describer word or adjective that we use in conjunction with phenotype or phenotypical is the word that will label the horse we are speaking about.

One of my horses is phenotypically a perlino. That doesn't mean she has proper form to function, or is pretty. Just that she looks like a perlino.