It's OK to get a 2nd opinion. FWIW, I'm not offended. Obviously, if you could 'clean' the crawlspace of warm air, you wouldn't have this problem.
Just for more of the physics ... Warm air holds more moisture than cold air (and it's relative too.) THe warmer the air, the more moisture it can hold. When the warm air makes contact w/the pipes and ducts, which are cooler than the air in the crawlspace, the moisture condenses OUT of the warm air. This is, basically, how a dehumidifier works. So, if you can 'cool' the space and/or prevent warm air from entering the crawlspace, you might solve your problem. Also, insulating the pipes and ducts should help. Be sure to follow the installation instructions on the duct-wrap and pipe-foam so you properly alleviate your problem. The cooler the crawlspace, the LESS water the air will hold.
Let me/us know how you make out. My best to ya and hope this helps.