
Google's John Mueller responded to a concern about having bad title tags and how that might impact your site in Google Search. He said on Bluesky "I don't think our systems have a "we don't like this one guy's titles" filter."
In short, John is saying there is no blacklist or system to remove a site or page from search just for having a bad title. Of course, if your title is not relevant to the content on the page, that can confuse Google and you might not rank well.
John responded to a quest from ‪Ryan Webb who asked:
Over the course of the last 3 weeks I have updated page titles to various pages (genuinely top 10 visited), usually I see these changes update on Google within 24hours but these changes aren't showing in the SERPS. SEO plugins and source all show correct.Titles, even yahoo, bing and duckduckgo are displaying the right title. But Google seems to have stopped updating. I would have put it down to some caching within the data centres but for 3 weeks now, it seems to long a time period! Is there some block applied if changes are made.
John replied to that saying:
The title link that's shown in Search is not necessarily the title element of a HTML page. We generate these automatically based on a variety of factors, to tweaking the text in a title element doesn't necessarily always result in the same change in Search.
Then this was Ryan's follow up question:
Thanks John. I appreciated there was more to it. Just I haven't seen this happen across so many pages before and wasn't sure of "blacklisting" so to speak.
Here is where John basically said there is no blacklist for bad titles - John wrote:
I don't think our systems have a "we don't like this one guy's titles" filter, but "we've seen some stuff" :). There are a lot of things that could go into this, so it's really hard to guess based on just what you mentioned.
Forum discussion at Bluesky.

