I have been into UFO research since 1999 and I have examined my fair share of UFO photographs. I am by no means an expert in the field of photography and I do not hold any degrees in the field. I am however a graphic artist and I can tell a photo shop image.
What you will want to do is download an image and take it into your photo editing program. Zoom in on the object. Look for pixels that are out of place and do not look natural to the image. That is usually a good indication that it has been photo shopped and it is probably faked.
Real UFO photographs will almost always show a distortion effect around the entire object. I believe this effect is caused by the objects movement through the atmosphere. Night time photographs are much harder to prove as the objects are usually present in the photo as a light object.
As you may or may not know it is very difficult to determine depth or distance with a night time photo. Unless you have a visible tree or corner of a rooftop it is usually worthless to try to prove or disprove the authenticity of the object. Therefore it is easier for a hoaxster to make and distribute a fake photograph and pass it off as the real deal.
Why would people do this?
It is probably so they can gain their 5 minutes of internet fame. I do know one thing with the invention of CGI it is getting increasingly more difficult to tell a real photograph or video from an amped up CGI fake. This takes away from the credibility of true UFO research.
Could it be a disinformation ploy on the part of world Governments to cover up and discredit true UFO sightings? I would have to say that this is entirely possible. Governments have been into the disinformation game for a long long time and they are quite good at it, so it would not surprise me to find out that this is what is going on.
Yes there are many different UFO’s that are real and are photographed almost on a daily basis and it really grinds my gears that people would take all of that time to introduce fakes into this line of research.
Keep looking up and capture whatever video and photographic evidence you can because real is always better than a fake.