I thought it would be useful to post some pics of the scent glands on a mature adult Syrian hamster.
Younger hamsters have less noticable scent glands and females too are less prominant. Pigmentation increases on the scent glands, ears and around the genitals as a hamster matures and especially in black eyed hamsters. The scent glands can appears 'wet' or greasy and mark the fur making it flat depending on how much scent is secreted.
Hamsters can sometimes be seen rubbing their hips on the cage sides, toys etc to spread their scent and they often do this just after cleaning out the cage to re-mark their territory.
They can be mistaken for moles, scabs and cancers but these are quite normal.
Dwarf hamsters have a scent gland on their tummy about the 'tummy button' position.
Paws, Black eyed cream satin demonstrates his scent glands (the fur has been blown apart to see them more clearly)
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Increase in pigmentation around the genitals
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Hope this helps allay some worries over these.