All kinds of wild reports come into the US government, including UFO sightings. These are "raw intelligence" and are worthless in and of themselves. The people making the allegations might be drunks, or unbalanced, or working for a foreign government or for a set of conspirators. (Feith picked up raw "intelligence" from all four of these sorts of sources).
Only once highly trained, seasoned analysts comb through the raw intelligence and weed out what seems wacky or unfounded or uncorroborated do you start actually to have what you might call an intelligence assessment.
I think it is highly likely that the "intelligence" on which Trump and Esper and secretary of state Mike Pompeo made their decision to off Soleimani was raw and cherry-picked, the product of the Trump equivalent of the Office of Special Plans.
It appears that Soleimani was actually coming to Iraq on a mission of negotiating less conflict with Saudi Arabia.