Nice guys finish....
Most everyone reading this might already know this....but I'll say it anyway:
I have led and observed many salespeople over my career. I've witnessed nice sales people and I've witnessed not so nice salespeople (jerks). Sometimes the 'not so nice' salespeople made more money than some of the nice ones, and sometimes the 'not so nice' salespeople struggled to earn income and the nice ones thrived. Being nice and helpful does not necessarily equate to income and results in sales. Being a jerk doesn't disqualify you from success in sales either.
One of the common denominators in my opinion for successful sales professionals is that they do the things they are supposed to do in order to make money. They prioritize their time and engage in activities that pay. They don't waste time, they don't pretend nor engage in 'feel good' activities which do not end in results.
For instance, let's say you worked on an assembly line, and you were supposed to put a nut on a threaded bolt over and over again. Every time you did this, you received X$. If you were a nice person, with high character and screwed the nuts on the bolts slowly, all the while chatting with those around you in a concerned manner..."How was your day...? Can I drive you to the airport...? Do you need help with this or that...?" You would earn much less than the jerk who could care less about anyone around him/her, and spent their time focused on screwing the nuts on to the bolts. On the other hand, it is completely conceivable as well that the nice person, with high character, worked diligently at their task, screwing record high nuts on bolts, while the jerk was busy complaining about the work and doing very little of it.
Who I'd rather work with, or who I'd rather be (nice guy or a jerk), myself, is a whole different discussion, but don't be fooled:
Successful sales people understand the activities that are required to earn commission and get results, and do them over and over again.