Detecting low-quality, user-created text content
There might not be a off-the-shelf package for detecting &quot;spammy&quot; or &quot;low quality&quot; because is it is relative to the context (as you already recognized).
One option is to use rules-based approach. Have a list of spam keywords. If any of them appear then stop the text. This is simple but also a limited approach.
Another option is to use machine learning learning to train a system to detect spam. The first step is collect thousands of human-labeled examples of both spam and not spam. Then apply natural language processing text classifier, naive Bayes classifier is a good baseline.