There are some free tools like scamvoid.com, tool.motoricerca.info/spam-detector/ and scamadviser.com these help to know website is a spam site or not.

You can do it manually as well. The following are most common factors to know it.
1. Using duplicate content
2. Irrelevant linking means a health website linked with finance site

Well, what you can do is keep a closer look at the DA and PA, don't build backlinks from the sites having low PA and DA. I guess just by looking at PA and DA you can eliminate the harmful backlinks.

Spamming is also posting links where it is not necessary to post links..

Just check ranking of websites that you are intend to submit

I think it's safe to say, I've seen just about everything now, lol.

Many online sites check the sites visibilities and status.

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