It's interesting to read how other people have perceived the interview process at Valutico and the social dynamics of the interviewers.
I personally went through a similar process and yes, this one is a practical session whereby you are challenged and it's demanding, but the impression I got is that it's simply replicating a real life client meeting and they want to see how you react and whether you will keep your discipline and composure. They want to know you don't go to pieces when put under a little bit of pressure which is normal in this type of environment.
If you turn up thinking the job offer is in the bag just because you have had some friendly initial conversations in the earlier rounds, that would be naive and your downfall.
I wouldn't deem the final interview to be tough and I didn't experience any rudeness or unprofessionalism, they are just thorough and meticulous in determining a strong salesperson from somebody who is going to moan, complain and cause endless problems within the team.
If you are precious about taking onboard constructive criticism, are a sensitive flower or prima donna, then sales in general probably is not a job for you