AC "Dirty Sock Syndrome" smell went away, is it actually fine?
It is a simple case of dirt in your evaporator getting wet.
You now know more than either of the idiots you had come out and check your system. This should have been done on the first call!!!
You can go to most home stores and get aerosol cans of coil cleaner to spray on the coils (the ones inside close to the air handler. The coil usually has a access panel just for this reason.
While you are at the store pick up some condensate pan sanitizer tablets or strips to put in the pan these also help to prevent mold in the pan.
The smell comes from dust and mold collecting on the coils and fins. When the ac is running these get cold and condense moisture out of the air , dirt, mold and water with air blowing over it. Very commonly said to smell like dirty socks. Search this site and you will find a few additional references.
Get new HVAC guys and if you decide to fix it and have success call the company and complain then the BBB as this is really simple.