It could be possible the organs were consumed by bacteria, but there still should be evidence of internal structures. I have a real fluke picture I got out of me, and will post it here:
Notice it has branching and stuff? This is typical intestinal type fluke. It was very small maybe 15 mm long if I remember. It was likely F. hepatica.
Sort of whitish-grey and leathery.
The flukes most people see, are more likely something pick-up from stuff we eat, and are not well suited for human infection. This is speculation. The common fluke of man which is large enough to fit most peoples description would have to be F. Buski which can grow large enough to be easily identified. They look like a living creature, and would gross you out to see one.
There are many, many parasites still to be officially recorded that infect humans IMO.