From a site on how to evaluate resources:
Indicators of Lack of Credibility
You can sometimes tell by the tone, style, or competence of the writing whether or not the information is suspect. Here are a few clues:
- Lack of Quality Control
- Negative Metainformation. If all the reviews are critical, be careful.
- Bad grammar or misspelled words. Most educated people use grammar fairly well and check their work for spelling errors. An occasional split infinitive or comma in the wrong place is not unusual, but more than two or three spelling or grammar errors is cause for caution, at least. Whether the errors come from carelessness or ignorance, neither puts the information or the writer in a favorable light.