First of all, congratulations to Nunez and Soares, who according to a mention in the Times, are now engaged. He apparently proposed after curtain calls one evening last week.
I have to say that it's generally not a good idea to judge a dancer based on one performance. Dancers are only human, so even the best dancers can have very off night. I've certainly had major reservations about a dancer one night and then felt completely different the next time I saw them dance.
Also, casting is one huge juggling game, so it's not always possible to have the perfect dancer in every role. Sometimes you have to balance out the assignments so everyone gets rest, so the partnerships are right etc., and there might not be any perfect way to sort out all the casting. Remember that the casting you see on stage also is reflective of who was able to rehearse when that ballet was being rehearsed and who is currently not tied up in major rehearsals for another ballet.
Not to mention that as an audience member, you don't necessarily know what goes on 'behind the curtain'. Unfortunately, dancers do go onstage injured, ill and otherwise less than in perfect condition - men especially, since companies tend to have fewer male dancers and they get 'beat up' from all the partnering. So a 'sloppy' performance could actually be the result of dancing on an injury or with a massive headcold. Which is why I, in writing reviews, tend to report the facts of the performance, but not judge unless I am really sure what's going on.
Whilst it may have been true in the past, I don't think it's that much easier for men in ballet these days, at least in many countries. And especially when it comes to the elite companies - there are enough candidates from within and without that they can be very picky. Most of the big companies also aren't going to promote someone based on their relationships rather than their talent, though it does still happen on the odd occasion. Just look at San Francisco Ballet - they hired Tilt Helimets, but didn't hire his wife/partner, Molly Smolen, right away. ABT hired either Beloserkovksy or Dvorovenko first, and the other later. And there are certainly plenty of husband & wife pairs spread out in rank.
As to the Bluebird, perhaps he was a) sick or b) injured and so having to exhert extra energy or c) was in great shape but had been rehearsing intesively all day/week/month for other ballets or even d) new to the role. Everyone has to start somewhere, and few people are spot on the first time out. Practice makes perfect, so if you never let someone try a role, they're never going to have the experience to do it well. And, darn it, dancing is hard work - I'd be surprised if a dancer wasn't breathing hard after the bluebird solo given the difficulty of the steps, the intensity of performing in front of a huge audience and the additional heat from all the stage lighting.
So, I would not rush to conclusions and be open to seeing a dancer several times before condemning or adoring them. One performance does not make a star nor does it make a disaster.