These are the best ways to determine the quality of a website
If the site has a Domain Authority higher than 20, it might be a good find. The higher the Domain Authority, the better, but don’t rely just on this metric; investigate the other ones as well.
Check how they are linking to third party sites. Only dofollow links will have an impact on your SEO. Nofollow links can be good for sending traffic, and get your website name in front of new readers.
Does the site look legit and trustworthy? Do they provide anything new and useful to their readers? Does the site have a good engagement with the users (social sharing activity or blog comments)? Would you be proud to have a link from that site?
If you are hesitant answering these questions, move on the next opportunity and don’t waste your time building backlinks that might hurt your rankings.