Google's John Mueller said on Twitter "Google doesn't use the spam score." This was in response to someone saying they have an 11% spam score (I guess on some third-party tool).
Here is the tweet:
Google doesn't use the spam score.
— 🍌 John 🍌 (@JohnMu) November 12, 2019
Yes, your site can have either one or more algorithmic penalties or manual actions but there is no over spam score that Google technically uses.
I believe you can have individual scores for different types of penalties or spam penalties, but the site overall probably does not get an overall spam score from Google as John said.
Back in 2006 we may have spotted a Google spam score but that was fuzzy and inconclusive and of course, that was 13 years ago and I am sure things have changed.
Forum discussion at Twitter.