Hrm....I've been thinking about this for a while, since we last had some of these discussions (which I really enjoy).
I think I have a pretty hypocritical definition of why I grow the plants I grow. I joke around about being a grex whore. The thing is, I'm all for genetic diversity, and for that reason, from a conservation standpoint, I don't really care what flowers look like, I just want there to be lots of plants available for polliination and survival.
When it comes to what I grow though, I have, I think, high standards for my plants. I admit I get trememndously annoyed with a flower that doesn't live up to my standards. If a plant doesn't bloom out the best I would hope for for that grex, why should I keep it sitting there taking up 2 feet of bench space? I have definite preferences in petal stance, for example. If there's roth in the breeding and the petals aren't outstretched enough - the plant's going to have to find a new home. Same with sanderianum hybrids. If the petals aren't long enough? I'll likely be looking for a better one. Then again, I've only had one bloom, my Michael Koopowitz, which was nice but the petals aren't long enough for me to really adore it. I am waiting for a second bloom before I raid Wendy's basement though.
This is a pretty recent thing for me (probably cause my plants have just finally started blooming) but I am serious about not keeping plants that don't meet my expectations. I recently sold a St. Swithin that was not acceptable, and I now have two new ones of, in my opinion, better breeding. One was purchased specifically because I have another plant with one of the parents that bloomed out spectacularly. If that parent brings it's beauty to this cross, I'm going to have one hell of a St. Swithin.
This also helps to keep things interesting for me. I'm pretty much at the end of my wish list, so as things bloom, I get excited about finding nicer examples.
Incidentally, I am much more serious about this with my Paph. multi florals (probably because the breeding standards are older and more set in stone?) than I am with my Phrags. As long as the Phrag. blooms out fairly well, I'm happy with it, but it still stands that I wouldn't keep my wallisii around for long if it had bloomed with 16" long petals. That wouldn't have met my standard for the grex.