In my experience, what FOs hate the most is a Captain who is constantly telling them what to do. Offsetting that, what airlines hate most, and I can hardly blame them, is an aircraft commander who fails to command and allows a significant incident to occur. Like all these things, there is a balance - some captains are better than others at achieving it. There are extremes - the stroppy and difficult personality exists in both seats, sadly. I sometimes am staggered at the way in which young FOs have spoken to Captains who have attempted to bring correction to them in a reasonable manner. Part of that is cultural - we live in a 'no one can tell me what to do' world and that has permeated into many young people's thinking. The airline industry is completely hierarchical and has no concept of that - inevitably that leads to difficulty. The bottom line is the Captain must be the Captain and any FO who has ideas to the contrary needs to be advised of his errors very quickly and clearly. However, there are ways of being in charge and that is where many problems can be avoided. I tend to back the view that some scope should be given to letting the FO have his way as part of the training process. Clearly the situation should not be allowed to get out of hand, but again there is a balance. In my experience the FOs that bleat the most about the terrible Captains they have to fly with, go on to be the worst and most difficult Captains to fly with. The lacked self-awareness as FOs and, possibly not surprisingly, go on to lack self-awareness as Captains.
Regarding A37575's tales of the long-defunct Paramount Airways - I am just so glad that the days of ex-RAF Chief Pilots sorting out their ex-RAF mates are largely gone (I am ex-RAF by the way). You actually have to have some training now - that seems to me a good thing. Sure some good guys got through, but some total berks got through too, who should never have got near the command of a commercial aircraft. But they were 'good chaps' on the Squadron, so they of course were given good jobs and then promoted early. Much criticism has been levelled at the likes of Turkish Airlines and Korean Airways for such practices, where ex-mil guys get accelerated promotion ahead of their civilian contemporaries - the reality is that it is only in the last few years that we have moved away from that in the UK. Airlines are into training people - thank goodness that is the case. We should be proud of that rather than hark back to the days of the 'old boys' network'. Apart from obvious technical advances there is a reason why 30-hour Sopwith Camel pilots dropped out the sky in their droves, and a reason why commercial pilots generally do not - training, training and training. No one is born a pilot - to be successful and live long in the role seems to require a strange combination of aptitude, training, knowledge, skill, experience and judgement. To ensure the right mix of those qualities requires a good apprenticeship with excellent training - not always easy to find.