Negative Comments and Complaints
However tempting it may be to avoid conflict on your social media page, do not delete negative comments or complaints out of hand. The poster may have a perfectly valid reason for their complaint so you should try and address their concern, apologize if necessary, and resolve the issue if possible (or put them in contact with someone who can). Being able and willing to respond to comments and complaints like this is essentially "customer service." Even if you do not have literal financial-transaction-making "customers" of your organization, the fans and followers of your account should be considered as such, in that you are responsible to them and should support their needs and requests when reasonable and viable.
Do not engage the trolls
While some negative comments can be resolved, there are some comments that are off-topic, inflammatory or extraneous which were posted merely to provoke others or derail conversation; the people who post these kinds of comments are known as social media "trolls." Although these comments are also tempting to delete, your first line of defense is your community of users, wait a bit after the comment is posted to see if the issue self-corrects. Often if a troll derails a topic or throws in an inflammatory statement the other commentors on the post will come to your aid and straighten out both the troll and the conversation. However, there can be cases where a comment goes too far and attacks others, uses racist, sexist, abusive, profane, violent or obscene language, or contains incorrect information. These kinds of comments (along with spam) violate W&M's comment policy, and they can be removed from the site if you choose. You are encouraged to link to W&M's comment policy (or a similar document of your own) on your social media site to use as a reference point if or when you ever have to delete a comment.
Don't let spam accumulate
Spam content comes in all shapes and sizes: comments, photos, posts by others, recommendations, Twitter followers. Spam messages are off topic, where the poster has no relation to your organization and makes no attempt to mention or reference your organization or field (i.e. someone ranting about a political issue). Often spam is an attempt to sell products or promote commercial, political or other ventures that (again) have no relation, reference, or relevance to your organization or field (on the W&M Facebook page we often see spam for "earn money fast at home" schemes). These spam posts also fall under W&M's comment policy. Letting "spam clutter" accumulate on a page is a sign that it is not being maintained, so clearing out those unrelated photos or posts by others on your Facebook page, or removing Twitter followers that are spam accounts, is a good way to show your page is maintained and active, and that your content can be trusted.