For the most part I don't think it is the job that is the problem it is the people. My mum used to work in a bank and the securicor van outside got a parking ticket, but then most traffic wardens wouldn't do that. You would also have to question the system. Traffic wardens are not there to raise money, they are there to stop illegal parking, so quota's should be irrelevant. Likewise, almost every Policeman I have known, seems to see themselves as better than the general public, whereas they are supposed to be public servants doing a service for the public. The majority of them have no idea about interpersonal skills and their attempts at diffusing situations usually make them worse, because they try to diffuse anger with force and authority, which will never work and is usually totally unnecessary. I have met other policemen and women who are lovely people.
As far as cold callers go, I love them all. They are the best stress relief ever, you can take out all your frustrations on them, take the **** out of them, lead them on then not give them the sale, waste their time. I do actually feel sorry for cold callers, because of the amount of abuse they get, but I equally feel like I am doing the individuals a service, because after calling me, they may decide to look for another job.
Having been a salesman, it is important to remember that you as the customer always have the control, because you make the final decision. Some salespeople will try to take that control away from, the particularly cunning ones will actually make you feel like you have more control while they are doing this, but never forget you have that control and use it to your advantage. Only listen to the salesperson when he is telling you something you want to know at all other times the information is for psychology and manipulation purposes only. By all means get friendly with salespeople, but only to the point where you can use it to your own advantage. In a buying/selling situation, there is no room for feelings, even though you may have feelings about what you are buying or selling. Fortunately most salesmen are insufficiently skilled or intelligent enough to use psychology and manipulation to their benefit and rely instead on building a rapport and winning your confidence or ideally your trust, but you should really look for the type that try to sell based on knowledge of their product/market and confidence in their product (look out for fakes, the sort whose trademark line is bull**** baffles brains).
I saw social workers were also mentioned. Again, I would say this is down to people rather than the job. Many people have had bad experiences with social workers, but again it is a difficult job and one which most people would only go into with the hope of benefitting others.
As with all jobs and all people, some do some things well others do different things well. If we were all perfectly vocationally suited to our professions, this thread probably wouldn't be here.