Each thread has had some common themes, but what's surprising is how different the problems discussed are. Here are a few of the best recent discussions:
Google no longer producing high quality search results in significant categories (twitter.com/mwseibel):
https://news.ycombinator.com/item?id=29772136
Search engines and SEO spam (twitter.com/paulg):
https://news.ycombinator.com/item?id=29782186
Ask HN: Let's build an HN uBlacklist to improve our Google search results?
https://news.ycombinator.com/item?id=29794372
DuckDuckGo Traffic - with spam discussion
https://news.ycombinator.com/item?id=29852783
Is Google Search Deteriorating?
https://news.ycombinator.com/item?id=29886423
Ask HN: What's Up with Google?
https://news.ycombinator.com/item?id=30031672
Tell HN: Google doesn't work anymore for exact matches
https://news.ycombinator.com/item?id=30130535
For some searches the whole screen on Google is now ads https://news.ycombinator.com/item?id=30213110
Disclaimer: I'm working on a search startup, so I have a clear bias, but one of the main reasons I am working on a search startup is because Google's results are clearly getting worse.