A couple of things to add to some already good advice from others -
If J could be feeling that he had a raw deal compared to manster, then how about you give J a bit of the attention he missed out on? Ask him if there's anything special he'd like to have for dinner one night. As a thought. I sometimes would get something with BF2 in mind (when he was living with us) so he wouldn't feel left out. I invite him and easy child 2/difficult child 2 round for a meal, I ask him which he'd like - roast chicken, or roast pork. Last time he wanted roast chicken, easy child 2/difficult child 2 wanted roast pork - so I made both. It all got eaten (leftovers next day) so it was no trouble for me, plus I used it to teach difficult child 3 how to cook the pork. Win-win.
I do tend to use food to signal a bit of extra TLC, but not quantity, so much as type. For example, I can use my bread machine to get me started on some sweet dough which I can turn into croissants, or brioche, or danish, or chelsea buns. I ask the person I'm trying to butter up, what their flavour preferences are. if it's chocolate, then I make a chocolate chelsea bun. If they want savoury then I do a pizza chelsea bun (NOT using sweet dough, but standard bread dough).
J needs to be kept occupied. You and your husband could get him to landscape the backyard (contract him to do it, include payment if he's doing a solid job of it as a professional labourer). A paying job of any kind would be welcome, a volunteer job would at least keep a work ethic and also provide experience. But it would have to be husband who negotiates this one.
Ask J is he would value your assistance in finding a paying job; if he would, what preferences does he have? A sort of, "If I happen to see something you might be interested in, do you want me to show you?" Does he need any support in updating his CV? It's handy to have one already prepared on the computer, so it can be faxed/emailed off at short notice (so your application gets in before anyone else's). Don't make it sound to J that you think he's a lazy layabout, an offer to help is nothing more than that. If he says, "No, I'm fine looking after myself," then don't push, just say, "That's cool. If you change your mind, I'm here for you." And leave it at that. After that if you Do spot something, let husband be the one to show him.
As for smelly feet - get manster back into socks. Avoid synthetics, use pure cotton or pure wool. If you use pure wool, do not hot wash, do not use a dryer, do not hang them outside to dry. Sorry. They shrink so easily. But by crikey, do they soak up the sweat!
Next thing to do - to wash smelly socks (or anything else smelly) - first splash/spray/soak with white vinegar. Get the cheapest you can, it's the chemical acetic acid you need, the sort of stuff you wouldn't want anywhere ner a salad. We keep a spray bottle of vinegar in the laundry. we use it to spray underarms on shirts, too. It can also whiten those yellow sweat stains. If you need to, use the vinegar then pre-soak in warm water overnight, then wash.
Socks - change daily. Make sure he has plenty. Be prepared to see socks as semi-disposable, and keep track of him changing them regularly.
Next - when he's putting his socks on in the morning, there are several steps he must go through.
1) rub anti-perspirant on his feet. Use a stick deodorant, those solid ones. Or a spray. Rub it between the toes. Allow feet to dry (if he used something wet).
2) Have a shallow tub that his foot can fit into (an ice cream container would do, if his foot is still small enough) and sprinkle his feet with baby powder. If you can get a special foot powder then it couldbe even better. If you can find one with antifungal stuff in it (we used to use tolnaftate, but we can't get it any more here) then it is best of all. Powder the feet, then sprinkle some more powder inside the sock.
3) At the end of the day, take off shoes and socks, put socks in the laundry. In a small dish of vinegar, if it's needed. Or spray with vinegar, then put them into pre-soak. Having the containers ready and helping him get into the routine, could go a very lnog way to effectively dealing with the smell.
The method (vinegar then pre-soak if needed) works for just about any other organically-caused smells. Just avoid using hot ater in the laundry, it cooks organic smells and stains into the fabric.
If you're still having trouble, then add some carb soda to the powder used in the feet, and put carb soda in the shoes. It not only helps to soak up sweat, it's a natural deodoriser. And if you need some more antufi=ungal help, buy a bottle of good old Aussie ti-tree oil (aka melaleuca oil). it's anti-fungal, anti-bacterial, it doesn't have too strong a smell (not like eucalyptus). You rub it onto the feet about the same time you rub on the deodorant block.
Going barefoot where possible is good, but not if it means taking shoes off and on all through the day. When out in public, leave shoes on. When home, take shoes off but put shoes somewhere where they won't offend. Let the shoes air and dry out, change the socks, give the feet a wash and an airing.
This regimen can fix the worst feet. If there is still a problem, see the doctor for fungal scrapings, or just bite the bullet and assume there IS a chronic fungal/bacterial infection, and treat accordingly.
Good luck!
Marg