Here is a summary.
Unless you have specific permission, you can not distribute, copy, publicly display, sell, or otherwise exploit or commercially use someone else's photos.
Photos posted on newsgroups are not yours to use. They are not in the "public domain." In fact, with extremely rare exceptions, no recently-created photo is in the public domain.
The "Fair Use" doctrine almost never excuses infringement of a photograph, particularly where the infringing use is commercial or where it hurts the market for the photo.
Copyright is normally valid with or without a copyright notice.
Copyright infringement is copyright infringement regardless of the infringer's motive.
People who infringe photographs are likely to be crushed in Court, and even have their businesses closed down.
Copyright violation may be treated as a serious crime, as well as a civil wrong.