It's easy to find plenty of counterexamples: cigarettes, Teflon pans, soda, cheap children's clothing with elevated lead, etc. And that's before we get into crypto scams, MLM schemes, etc.
Sure, but if you're taking kickbacks to promote something, it's a near certainty that's not what you're doing.
Like in this thread you have people asking what about retailers that take money for product placement, or how will people find products without ads? It's apparently inconceivable that retailers spotlight actual high quality products that they believe in and they do some industry research into what they should carry and actually stand by what they're selling instead of treating their customers like suckers to be sold.