A319 Captain reported a fumes event at departure gate during pre-flight. Flight crew deplaned; Maintenance was requested and a fumes report submitted.

Narrative

During pre-flight; and after starting the APU and selecting the APU bleed on; I immediately detected a strong 'dirty sock' odor. It is; unfortunately; a familiar odor; as I have encountered it a number of times in more than nine years on the A320. The First Officer (FO) had remarked that during her external inspection she noticed the APU inlet door was open. This could indicate that the proper APU shutdown procedure was not complied with. If the batteries are selected off before two minutes elapse after shutting down the APU; proper oil scavenging may not occur. I have heard that this can contribute to smoke; odor; fume events on the A320; but I do not know where I heard that; and the correlation in this case may be coincidental. The fume odor increased in intensity; and I experienced discomfort in my eyes and throat. After confirming the odor with all of my crew members; I directed them to gather their belongings and exit the aircraft. I called Maintenance Operation Control to report the event and completed the form on Device. I also alerted my dispatcher and the on-call duty pilot. I after a while I received a text from Pilot X. I called Pilot X; who wanted to discuss a possible engine run to help locate the source of the fumes. After being informed of the risks; and the very specific safety precautions for an engine run; I declined. Incidentally; it was my previous event in ZZZ1 and engine run that resulted in a safety advisory email to be sent to all pilots regarding such engine runs.I do not know [the cause]; but fume events seem to be particularly endemic to the A320 fleet.Suggestions - I think there should be a major revision to our SOPs for fume events. It should be an important topic.