Just curious to know if she has ever been pied in any of the episodes of the Simpsons

I dont recall her getting pied no. But Ive not watched this season yet so who knows.

But she has gotten muddy (decent coverage) in the Season 28 episode "Pork and Burns".

Best opportunity squandered was the whole "Pie Man" episode but that was just Homer going around pie'ing other men of Springfield.

Closest you'll get to seeing Marge pied is some great fan art that Bakerman did of Marge getting pied, if that's your thing.

I'm pretty sure there was an episode not sure which series , cooking or school competition themed where there was some mess or water plot, and there's an episode about naughty cakes I think.

I bet somebody on here could make some Ai images of what your looking for.