As you probably know, Google Places is a business directory that allows business owners to create and edit a free page including text, photos and other stuff. All of this may appear in the main search results but also in the Google Maps program.
All this does come at a price though:
Google allows anyone to post a comment and it will appear beneath your free listing. They do not check each comment and are probably not liable for any damages caused. See section 230(c) of the Communications Act.
They will normally only remove a comment if it is illegal or advocates hate or violence.
Contacting Google Places
To report comments that are against Google policies, just click “report as inappropriate” next to the comment and select from the options.
If you see a Places page that contains your copyright content you could consider filing a DMCA take down request such as this.
For incorrect information on a listing, you can click “claim this listing” and remove/edit the text or photos after you have verified ownership. You may be able to click “edit this place” and make some changes if the owner has not already claimed the listing.
Where Did This Page Come From? I didn’t Create It
Google creates Places pages by pulling in existing information from third party websites that already contain your information. Then then allow you to edit the content/photos etc if you so wish. Comments are generally considered to be the responsibility of the person who wrote them.