The UPSIT Test (scratch and sniff odor home test)

Probably the main reason that body and halitosis is still around, and metabolic body odor is not accepted as a medical problem, is because usually the sufferer cannot smell themselves. Most with metabolic body odor would seem likely to be transient, and on a visit to the doctor there's a good chance they do not smell at that time nor know how to 'provoke' smelling. So as far as the medical industry grandees are concerned, there is little evidence of the problem.

Usually fellow sufferers, possibly only of the same type of body odor or halitosis, cannot smell each other either, and possibly it is the case that perhaps a small percentage of non-smelly people can smell sufferers mostly either (for instance, perhaps genetic carriers of a metabolic body odor cannot smell sufferers often). Dr John Cashman estimates that perhaps 8% of the population cannot smell trimethylamine when others can. As examples; perhaps those with 'mild' isovaleric acidemia cannot smell someone else with the same problem, but they can smell someone with trimethylaminuria ... and vice versa.

This 'selective anosmia' does not seem to apply only to metabolic body odors, but to all types of body odor and halitosis. For instance people with 'classic' body odor or 'classic' halitosis (the surface-type odor problems) seem not able to smell themselves. It may also seem likely that in these cases that 'loved ones' cannot smell them either. For instance, perhaps you know someone who is well respected and has a wife and children but has a habit of developing a body odor over a number of days then it disappears (after bathing) and starts again. The question is, can his wife and children smell him ?

In medical terms, the only current explanation would be 'anosmia', where people cannot smell certain smells. The current 'home test' for this would be the University of Pennsylvania Smell Identification Test (known as the UPSIT test). This is basically a 'scratch and sniff' test of 40 odours. The University of Pennsylvania has a smell and taste clinic, seemingly opened by the NIH. Someday perhaps there will be body odor and halitosis research centers and clinics opened by the NIH.

The UPSIT can be purchased from sites such as this for around $50 including everything needed.
Example seller : sensonics.com UPSIT Test

Although it may be an interesting test to do, it's not known if it will provide any clues to the mystery of metabolic body odor and halitosis (or other types).

Note : Unfortunately, although most body odor and halitosis sufferers cannot smell themselves, the anecdotal evidence seems to be that they can smell the smells from other sources other than through the skin. So the 'body odor/halitosis anosmia' does not seem to be as simple as being unable to smell certain smells, period. For instance, most people likely can smell a fish rotting, which presumably means they can smell trimethylamine from that source. There is no current explanation for this 'quirk'. A speculative guess would be that if your bloodstream has a certain level of 'smelly' toxins, then the 'smell receptor bar' is set higher than a normal person.

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Other links
University of Pennsylvania Smell & Taste Center