Ask Google for "ufo hoaxes" or "ufo hoax photos" and you will get a LOAD of sites.
If you read them, you will find some that defend UFO photos with claims similar to
"There's no evidence that it is a hoax, so it must be genuine." If there is no evidence
of hoax, there are two possibilities: either it is genuine OR it is a hoax good enough to
escape detection. In this world of very capable image manipulation, a photograph by
itself is not adequate. One research reference noted that, for any UFO claim to be
seriously considered, you must rule out hoax. This is almost impossible to do now.
Software like Adobe Photoshop is so good that really excellent results can be achieved.
Look at this site
and get a load of samples.
Another web site, "Experimental
UFO Hoaxing, tells a story about UFOs and lack of critical thinking that all should read.