I can look at it from 2 perspectives, firstly from the point of view of someone who was once a member of 2 "white collar" unions in 2 different countries, and secondly, as someone who sits down on the opposite side of the table from unions on a regular basis.
In terms of being a member, I was never impressed with the local union reps. Some were too firmly in the pocket of the employers (especially in the UK) to rock the boat, others were just gobdaws. There were some good deals done in terms of payrises and bonuses, but there was an element of "short-termism" in the deals, money up front for long term benifits being eroded for example, and the impact the deals had on the long term cost base of my employers only meant that cost cutting and reducancies were inevitable at some stage in the future.
In terms of sitting opposite union reps, there are 2 kinds. There are practical people, often who've worked in business in the past who are always open to getting a deal done and accept that we have a business to run. Often, you'll have the formal "negotiations" drag on with the real deal being hammered out over a cup of coffee across the road. The 2nd kind are the worst, the kind who bring idealogical baggage to the table, who are convinced we are out to screw "the worker" (whatever that is) and couldn't care less what the deal means in real terms as long as they can be seen to have got one over the management.
In fairness, a good sensible union rep can be a benifit to a business in terms of managing staff expectations. I've seen them tell people not to take a case for eg, bullying or harassment or over a disciplinary matter because they weren't going to win because either nothing happened or the action was warrented and that they should "cop themselves on". I've also seen bad reps lead people into actions that were only going to end in tears for the staff member concerned
