My rules for Facebook posting and commenting...please note these are MY rules, and I base them off 20 years of professionally managing online forums and as the former Chief Sysop of PC World Online Forums in the 1990's, where I was known as PCW David.
2. What you do on your timeline within the scope of what Facebook allows, is acceptable. It may not win you friends or likes, but it is YOUR timeline.
3. Deleting unwanted comments on your timeline is acceptable. Again, it may be unpopular and even cause you to lose friends, but it is your timeline. We'll cover better ways to handle negative/unwanted comments in a moment.
4. Automatically commenting about something controversial on another's timeline is "stupid", if you haven't really thought it through before doing so.
5. The fact you disagree with something, does not mean your comments will not be deleted on another's timeline. This also applies to comments that you know are not correct. Once again, it will serve you well to remember that timelines are like homes. EVEN if they are giving out wrong information, they can still delete your comments....like it, or not.
6. Consider dealing with controversy on your OWN timeline, not others. I'm not saying it's OK to call them out on your own posting and timeline, although that is up to you... and has consequences in doing so. You may be OK with the consequences, but know they exist.
7. If someone has posted something wrong or misleading, consider a private message to the person. They may not know what they have posted is wrong, and they'll appreciate the privacy in discussing it. On the other hand, they may not care for your opinion in which case if you feel the need to correct bad information you'll usually go further on your own timeline. Why? Many people have similar thinking friends and they may not care for you calling out their friend.
8. If you posted something controversial and ASKED a question....well... you asked a question, and yes it's your timeline and you can still defend it as you see fit, but once again...you asked!
9. You may think that because you know the person and you have bantered with them before on their timeline, all is OK and you can keep arguing... Maybe so, maybe not... Many people will "tolerate" comments for a while, right up to the point they move you to their acquaintance or restricted list. Don't take for granted friendships when it comes to being respectful.
Again, think of timelines as homes.
I'll be adding more to this on a continuing basis...