Falanu Hlaalu!
She likes doing it with corpses. She is also a Hlaalu from Morrowind, which helps explain why she is there, at least. The Hlaalu clan is, to my knowledge, the most accepting of other cultures/salesmen-like, which also explains why she owns her own business. Anyways, in Morrowind, it is sort of really disrespectful to knock boots with corpses (the whole ancestor thing), so yeah.
In Skingrad, the fine is only 500 septims. Which is nothing to her, because she likes doing it with corpses.
That is the logical explanation.
The other is that it is just a joke, to make you go "Hey, what the hell?" then laugh about it.