If a sales person makes one sale it doesn't matter if the organization's reputation is overall negatively impacted, they got paid and reputation is something that takes years to really see large impact from. Given that sales people work on commission, or at least largely so, and may not even work at a company for more than a few years, it makes sense to aggressively pursue every potential lead. You'll remember "DD has aggressive sales" and not "that one sales person is super aggressive".
I'm not sure how companies should fix this other than increasing base pay and decreasing commission payouts, but obviously that has its own incentive issues.
I guess a company wide policy of "never contact someone more than X times per Y timeframe" and "never ever ever contact someone via cell phone wtf" would help.