I just got an email from a company offering me a fixed annual fee to display an ad on one of the pages on my personal website. The email was professionally written, their website looked legit and I have Google Ads now which pay me almost nothing so I decided to ask what kind of ad, how much they'd pay and so on. They promptly replied, said they'd pay from 120-175$ annually and this would be a text-based ad, and they were only interested in one page on my site. There were two options for me:
1. Simple text based advert, which will "appear in the content area of an already existing page on your website".
2. Their team of content writers could write a new page to put on my site, which would fit my content.
To show me an example of their ads they sent me a link to another webpage, which they said had an ad for a company. I checked it out and it had a link to the company in the middle of an article, right in the text, with no mention that it was an ad or anything. It just said something like "We used Company X and their staff was so helpful".
So, my question is, how common is this practice? Now I feel like every time I see an offhand mention of something with a link, I'll think, wait a minute, did the author just get paid for that?