My opinion is based on the fact the OP came here for advice, and these statements, which indicate that whatever efforts the BF may be making, they are not adequate. Also, depression that flares up once every two years and lasts long enough for the BF to be fired and for other people in his life to consult the OP leads me to believe he is actually depressed about one quarter or more of his life, which to me is significant and recurring, not rare.
"I've gotten comments from people (his friends and my family) asking if I could address the body odor situation with him, and I've tried, but my point has never gotten across. He's also lost a job because of this, and that didn't inspire any changes either. My attempts to fix this have included buying him expensive manly bath products (he loves using them when he's feeling his best), gently suggesting that his hair would be so soft and shiny if he washed the gel out every night, setting a schedule for our day (run errands, come home, both of us shower, then we go out on a date), asking him not to hide dirty clothes, making sure I clean out the dirty clothes spots everyday and putting them in the wash, suggesting counseling to help with his depression, and I've even tried to tell him flat out that I'm concerned for him and his hygiene and that I love him so dearly and that taking care of himself might help build some love and respect for himself which might help to pull him out of his depressed phase even faster, and he's had a former boss confront him (he came home and cried and felt horrible for weeks and he wouldn't tell me exactly what she said, but I know she wasn't the queen of tact, so I can only imagine). After that boss confronted him, he didn't change his habits and they slowly started giving his work to other employees until eventually he had no work and made no money and had to quit and find a new job."