Layoffs will lead to some negative posts about a company, expect them and ignore them. Suing over negative comments will lead to nasty court fight that you stand a decent chance of losing by legally and morally. Ignoring them will not draw attention to the comments as the only people who are likely to even read them are people looking at you specifically. Kraken made sure I heard of them negatively and I have no interest in them, very stupid of their manglement.
As far as reviews on Glassdoor and similar sites, expect the happy employees to post comments less often than the disgruntled and ex employees. In other words, take the reviews with a bit of a grain of salt that they are probably skewed.They are like any other online rating and should be used as such, useful but should if possible not be the only source of information. I would look at the general tenor and trends in the comments as well as the most recent.