Google's John Mueller said in a video hangout the other day at the 50 minute mark that redirecting a low quality page to a higher quality page won't hurt the higher quality page. Google will evaluate the content on the final page, the ultimate page, and not evaluate the content from the redirected page.
It is a short blurb in the video, so here it is when he starts talking about it:
Here is how Glenn summed it up:
Via @johnmu: If you redirect lower quality content to a newer version that's higher quality, Google will evaluate the content it finds on the the destination page. i.e. Google will evaluate the NEW content for quality, not the old: https://t.co/ptSHlY8SKG pic.twitter.com/U3DwJ75qAT
— Glenn Gabe (@glenngabe) March 27, 2019
Here is the transcript:
If a story has been redirected because it was thin content and many years old, do the negative effects of the article kind of get forwarded on with the redirection?No, not necessarily.
So especially when it comes to content we look at the content that we find on the ultimate page that we land on. So if you've removed content, if you've cleaned something up, and I guess that happens automatically. If you redirect that page and the old content is no longer there and we only have the new content then that's perfectly fine. So that wouldn't be anything that would kind of be carried on.
To be clear, this is just about the content, not necessarily the other signals that may or may not hurt or benefit you.
Forum discussion at Twitter.