Depends on how relevant are the ads. I think it augments the business because now businesses are monetizing majority of visitors in some way. It's sustainable for long term if the ads are relevant enough for users to not drop off. Ads and trust are inversely correlated agreed, though looking at Uber and Amazon, I am not sure if that is true for every case. I might be an outlier, but amazon ads after I search for a product are actually quite useful. And probably why advertisers get a good ROI (evident in growth) and users aren't turned off by it (evident in sales revenue). Relevance score for any ad would matter for the company.