rank odor
膻 centers on a strong, unpleasant smell, specifically a rank or foul odor, often associated with meat or animal fat.
膻 combines the flesh radical ⺼ with 亶, which likely contributes the sound. The character is associated with the smell of raw meat or animal fat.
The flesh radical ⺼ on the left hints at meat. Picture a piece of meat that has gone bad, giving off a rank odor that fills the room.
For タン, imagine a tanning hide giving off a strong, rank smell: tan -> タン, and the odor is as pungent as the tanning process.