I can assure you that spam score is a completely irrelevant metric by an irrelevant company. I have zero clue how they are still in business after all these years.
You might as well go to Google and type "0 to 100 number generator" and consider that your spam score. Might even be more reliable.
If you want these domains for SEO purposes, then make sure you check their history through Archive or Domaintools. Hosterstats, that is hosting history, will tell you plenty as well.
Once you see signs that the domain has been "abused", it's better to stay away, IF you want it for SEO that is. Do not rely on the spam score.