The scummy sales person is a stereotype. They exist sure but if you've ever worked with a good one they can really help particularly if you're buying something complex. I used to work for a company that sold complex manufacturing equipment and without a salesperson theres no way most customers would know what they needed to maintain it etc.
As an engineer i hate both, technical sales never have an understanding of their product and are never able to answer any of my questions (because i've read through the datasheet as their words are meaningless to me) but they are mooooorrrreee than happy to schedule an in person meeting to come to my office and show me their product line.
Tell me what i want to know or find me someone who can, im not going to buy 10,000 of whetever if i cant even determine if they will work for my use case.
The last time i had to deal with one of these assholes it took 3 phone calls and 2 emails to get a simple answer which wasnt in their datasheet, which was all of one page long.
My favorite experience with technical sales is we had these component guys come in, they had openned up our product and wanted to show how much better their "equivalent" components were (genuinely a great idea), but they had no context as to what the components were being used for so they all fell flat.
In my experience both are only a waste of my time.
It's been my experience as well, especially in the web space (I'm not a web person), but everywhere else too.
Sometimes I like to chat up sales people if I must, just to see if I get anything interesting out of them, but usually I end up annoyed and bored at their hustle because they're just saying whatever they think I want to hear, and don't really know anything of substance about what they're pushing.
When my dad and uncle wanted a website done and thought I could do it (again, not a web person) because I was their "computer guy", we ended up trying one of those "Let our expert team get you going!" services pushed by a hoster. (Fatcow, in this case, may they burn if they're still around.)
The sales guy had us thinking we'd be in business sooner than later. They'd have it handled. They were pros. Awesome! I could learn a little bit about managing all this while they'd get my non-technical family set up with the hard parts to start their venture.
...The result was a lackluster, barebones Wordpress site.
There was no consulting or advice, no educating about how the web worked or how things are usually done. Weird hacky custom code for everything from video uploading to payment processing.
Zero design went into this and the best part of it was the logo, which my uncle hired a freelancing college student to do.
All my family got was some number that connected to a very annoyed team in India who just wanted to connect your request to whatever was closest on their menu and charge you a few hundred up front for it. They just assumed you knew exactly what you wanted and would bill by the hour to write some ugly custom JavaScript / PHP.
(Man, if they just implemented existing plugins it would have been better...)
They wanted to charge a ridiculous fee for adding an SSL, and basically shrugged me off when I called to ask how to do it myself, after we all agreed this was for an e-commerce purpose in the first place.
The website never truly went live, they got a lot of money, and the only $20 we "made" was from testing the checkout function.
The consequences of this are why, to this day, I just teach myself enough to do whatever it is I want to do. The only difference between a good salesman and a bad one, is that the "good ones" are simply clever enough to evade your bullshit detector.
The whole game is to make you think you're hiring some friendly pro who's got it all covered, but in the end you were better off doing it yourself anyway.
I was a naive teenager who lacked ability, just trying to help out my family. I still feel guilty to this day.