Don't know about imgbb.com, there terms are as photobucket, and the knid of content used will be removed, over time
Terms of use of Imgbb service
What cannot be uploaded to Imgbb servers:
Copyrighted images if you don't own copyright for it
Violence, racial intolerance, or advocate against any individual, group, or organization
Any other images that might be considered illegal in USA or EU countries
Also, don't use Imgbb to host image libraries you link to from elsewhere, content for your website, advertising, avatars, or anything else that turns us into your content delivery network.
If you are not sure whether image you want to upload is allowed then do not upload that image. All uploaded images are checked by staff and images that violate terms will be removed without warning and uploader of such images might be banned from website.