Something interesting I noticed while watching people run SEO analyses on their sites

I shipped a small SEO analysis tool yesterday and have been quietly watching how people use it.

What surprised me: most sites that “look fine” fail in very boring, invisible ways.

Not obvious stuff like missing titles — but things like:

- canonical URLs that technically exist but point to the wrong variant

- internal links that silently break after redirects

- metadata that’s present but inconsistent across templates

None of these throw errors.

Nothing crashes.

Google doesn’t warn you.

But rankings slowly bleed.

It made me realize SEO failure is usually not dramatic — it’s gradual decay.

Curious if others here have seen similar “nothing is broken but traffic dies” situations.