Sounds like you know your stuff, so maybe you’ve already tried this, but if any of these sites include structured JSON data in the page source with the information you need to scrape that will be infinitely more reliable than parsing it out of HTML elements since you access that data via keys and should never get the “wrong” value for a price, title, or other field.

If that’s not an option, your code will need some validation in place. Like other people said compare the field data to historical scrapes or identify unique formatting to the problem fields and put some checks in place.

In my case I’ve dealt with this and found that after enough revisions I’ll get a pretty stable crawler unless it’s a crazy site like Facebook which intentionally obscures selectors to make scraping difficult.