I swear by Natural Magic odor absorbing gel. (Link below). Similar products like Citrus Magic work, and I just found a new brand I've tried (Clean Air) that seems to work equally well as Nat Magic. Bought a vintage Drexel bedroom set a couple years ago, dead of winter so I couldn't air it outside. It was beautiful and pristine but the inner drawers of one dresser had a perfume odor that nearly bowled me over. I cleaned it with mild dishwashing liquid and a tad of bleach just for kicks (and I wanted to clean it anyway). Odor stuck, so I put 3 containers inside the dresser, kept the drawers cracked open a bit (air flow enhances the odor removal with these products per the label) and left them there for several weeks, rotating between all the drawers. Took awhile, but it completely removed the odor. I've used it in all kinds of scenarios for all kinds of odors (pet, smoke, mildew, rental houses when showing, cars, inside furniture, etc.) Never lets me down! You can find these products at most hardware and big box stores like H Depot and Lowes has a good selection. About $1 cheaper at big box stores vs smaller hardware and paint stores. Oh, also Gonzo odor absorbing volcanic stones. You can get them in small bags for closet size and larger for room size. I've seen those at Home Depot. Seem to help, but the gels mentioned above are tried and true for me. Here is a link that might be useful: Natural Magic

That's why I prefer white towels. All whites or lights that do not need to be handled gently (underwear, towels, socks, kitchen towels) I use Tide with bleach/hot water. That alone should do it. If not, use liquid bleach. However, the Tide is the easiest and not quite as rough on the clothing. I use warm on any other clothing that is dark or less sturdy. Cold only on the darkest darks or gentle items. Rule of thumb, use the hottest water that your clothing can take. I'm not familiar with "Purex". For anything other than something that can take bleach, I use Cheer with colorguard. Never any problem with mildew smell. Btw, if you line dry, don't let your clothing sit in the washing machine without immediately hanging it. The longer a fabric stays wet, the more likely you can get bacterial growth. Even bleach water won't 'sterilize' clothing...but using it greatly decreases your odds of mildew. I would also say that cool weather line drying, especially if there is high humidity is going to make your clothing take much longer to dry. I never do this except for delicates. Immediately into the dryer. But if you do do it, put it outside or in an area where it will dry as quickly as possible. Never would do this in a closet. As to your Dh's towel? Wash more frequently. Again, he's got a wet towel that's just hanging around growing things.

Suziesnowflake is spot on -- if the PO's had to replace subflooring, something's wrong. The problems with window flashing are espeically bad in stucco houses because the stucco traps the moisture inside. Our house was 6 years old when we started noticing a pretty strong musty smell in several of the bedrooms and in the laundry room. We had noticed the smell on and off for the past couple springs but it would always go away before we'd get worried enough to do anything about it. That year, the smell stayed and got stronger. We had no signs of water intrusion anywhere and no previous mold problems. We took the electrical outlet plate covers off the wall and noticed that the smell seemed to be coming from inside the walls. Also, the screws inside the outlet boxes were rusty. We had several contractors out and none of them could find any sign of a problem - a few of them even said I was crazy (not so bluntly but that was the implication) becuase they couldn't smell or see anything. Finally, one day, we pulled a piece of slightly punky wooden trim off the outside (the contractors all said that that's just a normal thing that happens to wood trim and we should just plan on replacing it once in a while). While we were removing it, the crowbar went through the house. All of the sheathing was completely moldy and rotten - you could put your finger through it. We ended up spending over $100K (none of it covered by insurance) to replace the entire outside of the house - we stripped it down completely to studs and drywall. Some of the studs had to be replaced. We had to replace all the insulation - it wasn't wet, but was holding the musty smell. We washed the worst of the mold off the studs with bleach. We reinstalled insulation, new sheathing, and new siding (while PROPERLY flashing the windows). It was a nightmare and we're still recovering financially and emotionally (I'm a stress eater and I packed on a good 40 lbs in less than a year from the ordeal). I hope that your problem isn't this serious, but if your home is recently built (last 15 yrs or so), there's a good chance that it is. After my hard-earned lessons on flashing and homebuilding techniques, I can even today drive around to new developments and watch new million-dollar houses being built with improper window flashing. This is going to become a big problem over the next 10-15 years as all of this hidden moisture starts to manifest itself. I'd definitely do some investigating since the sooner you catch it, the less there will be to fix (and maybe you can go after the previous owners for some of it if you can prove they knew there was a problem). Start by taking the outlet plate covers off in the rooms with the smell and sniff -- is the smell stronger in the outlet boxes? Are the screws inside the outlet boxes rusty? If so, you've got moisture in your walls and that's not good. I'll link to my website if you want to look at the gory details of our house....but it's not for the faint-hearted, LOL! And if you do look, remember that even with all that damage and rot, we never had ANY signs of moisture or leaking inside -- all we had was the smell which, like you said, was worst in the change of seasons (spring especially). Here is a link that might be useful: Worst case scenario....

Use Mrs. Meyer's Clean Day lavender (they have other fragrances). I use a laundromat and have asthma, COPD, and very sensitive skin (I break out in hives and wheeze with most detergents. I use a three load washer and it calls for a tablespoonful a load but I use a bit less, and Downy free and gentle softener. The lavender smells good, but it's not overpowering and doesn't 'linger' like chemical fragrances, it just smells clean. In fact the clothing I wash only smells very faintly lavendery a few days later.