It's generally not worth it to post any political opinion on FB lest the trolls appear. What has been most disturbing is the otherwise normal people, including those considered friends, who are delighted to berate and bully you for expressing a political opinion.
Having said that, sometimes there are issues that are just so near and dear to my heart that I have to post information about them. So far most of these have not attracted the vitriol that I feared. Of course, election years are the worst. Urgh!