Earlier quoted context omitted.
> I am looking for a product, I will look for it. Note that this attitude is what pushes some sales teams away from reaching out to line management, and towards C-level-targeted sales. If you hate "golf-cart sales" outcomes where a C-level forces a solution down your throat, then learning how to communicate with sales people will richly pay off. It is part of managing upwards, by short-circuiting sales warm approache…
In an ideal world, spammers wouldn't exist. Or at least C-level people who respond non-negatively, thus encouraging them to keep on doing it. :( If people wonder why spam is a problem, it's pretty much because enough idiots respond to keep it worthwhile.
Generally speaking, C-level relationships are cultivated over a long time with the kind of sales and marketing budgets you've read of; dinners, sporting events, wine tastings, etc., with some proven sales account manager. However, it takes a lot for some sales opportunity to rise to the level of bringing it to the attention of this relationship. If you want to stop what you call spamming, then your job is to manage upwards by ensuring pain points do not rise to that level. This keeps the sales account management activity focused on the numbers when the support contracts come up for renewal.
However, if you have not been successfully managing upwards, then lines of communications have broken down between C-levels, or between CIO to your level. The first you can't do much about. The second is partly within your control. If you ensure your manager has nothing from the business to complain about that can be addressed within the solutions you are responsible for, then you've done what you can about it; you can't fix what you aren't told, after all. Where most technology-oriented staff misstep is they think they need to hear it from their management; the staff who successfully short-circuit pain points coming up to the C-level's attention realize that they can also ask, and more importantly, demonstrate they can communicate and coordinate between departments and people to help address those business-oriented pain points before they percolate upwards.
Where these sales account managers pounce is when the pain points become so grave that the C-levels hear about it and feel they have to "do something" about it, and "it" is a competitor's solution. And if you really like that competitor's solution, and hate the idea of switching away, be on the lookout for a call from one of the sales reps assigned to help that sales account manager. If you've even heard about the pain point, then you will be able to help drive the discussion, and most of the time if your favored vendor is on the ball, close the window of opportunity for the sale to be floated up.