Air Carrier Captain reported a fumes event upon arrival for preflight. An AML discrepancy was submitted which resulted in a communications breakdown with Maintenance Control and an extensive delay before departing.

Narrative

We arrived at the aircraft at XA20L for the first flight of the day for the aircraft. The #2 pack was operating off the APU bleed. A moderate dirty sock smell was noticed immediately upon boarding; with the odor increasingly strong farther aft. A review of the logbook revealed several 'odor' events going back at least two weeks. The latest one was two days prior; after which an attempted pack burn caused pack #1 to overheat. Pack #1 was then deferred. I refused the airplane due to ECS (Environmental Control System) contamination. I contacted Dispatch to get the ball rolling on a tail swap and he forwarded my call to the Maintenance Controller.The Maintenance Controller informed me that the airplane was airworthy and to call my Chief Pilot and then hung up. A few minutes later; the duty Chief Pilot contacted me and we discussed options. Since I hadn't yet written up the new event; the airplane was technically airworthy; so I wrote up the fume event; filled out the odor report form; and awaited further developments. About 1 1/2 hrs later; we were informed that the aircraft was ready; so we returned. The corrective action performed was to defer the APU. Maintenance did perform an engine run to operate the remaining pack from the engine bleeds to check the pack for odors. This was the extent of their investigation. There was no ECS decontamination. Consulting further with the duty Chief Pilot presented me with 3 options: accept the airplane; refuse the airplane; or verify the maintenance work by performing my own engine run.I found out later; but was never once explained to me at the time; that the procedure for a confirmed ECS contamination event *requires* a decontamination and a thorough check to make sure further contamination is halted. Instead; I was to take the word of the Maintenance staff that all was correct since they were following FAA approved procedures; and the corrective action actually performed was appropriate to 'get the flight out'.I was deeply uncomfortable with the situation; seemingly the only person involved (other than the rest of my crew) to be so. Certainly not a single layer of operational support (other than Dispatch; who was powerless) - including Line Maintenance; Maintenance Control; or the duty Chief Pilot - conveyed any sense that what was occurring was in any way cause for concern or further inquiry. I was told repeatedly that I would have final say; but I felt completely unsupported that my professional judgment was in any way welcome or worth heeding. Calling a safety timeout is one of the most important decisions I need to make as Captain; and in this case; it took four hours and an hour or more of virtual gaslighting to finally be able to make it stick. I felt as though I was the only person out of line; and who was I to question the professional judgment of everyone else? It was the closest I have felt to pilot pushing in more than XX years with the airline.