YMMV / Charmed S5E1 A Witch's Tail Part 1

• Best Known for the Fanservice: The episode sticks in memory for Phoebe being turned into a mermaid, and getting a gratuitous tilt along her body to show her breasts only barely covered by scales.
• Evil Is Cool: The Sea Hag is a very cool villain, with the power to control water, cause rainstorms and tidal waves, and turn into water to avoid physical damage.
• Fetish Retardant: The two scenes of Paige getting wet are very obviously an excuse to have Rose McGowan in a Sexy Soaked Shirt, and the blatant-ness of it is more amusing than arousing; especially since she walks into an office environment wearing an outfit more appropriate for the beach.
• Franchise Original Sin: This is the first of Charmed's forced sexy transformation episodes in the fifth season, as well as the start of the show going Lighter and Softer. The mermaid transformation however is a lot more beloved or at least tolerated in the fandom for having some Nightmare Fuel to keep the plot in line with the show's tone and it's woven into the story with a lot more justification (representing Phoebe trying to run from her feelings), and generally being enjoyably escapist. This puts it in contrast to episodes like "Y Tu Mummy Tambien", which has Phoebe donning a Sultry Belly Dancer costume for no reason beyond Fanservice, or other transformations that brought the show into Denser and Wackier territory.
• Money-Making Shot: Phoebe leaping out of the water in slow motion to throw the shell at the Sea Hag. It made it into the credits and is especially memorable.
• Trans Audience Interpretation: Mylie is hiding her mermaid identity from Craig, and refers to herself as "a genetic freak", spending the whole episode afraid he won't accept her when he finds out. When she does come clean, it's not unlike an Unsettling Gender-Reveal, and Craig has to be gently coaxed around to looking past that and admitting his love for her "really beautiful heart". When he does, Mylie becomes a human woman permanently.
• Unintentionally Unsympathetic: Phoebe blames Cole for finding a way back from the demonic wasteland, when she was the one who condemned him to essentially hell with no afterlife, despite him being an innocent who got used by everyone including her. She even resorts to slashing his hand with a letter opener! While the next episode would reveal her to be still in love with him, making this a manifestation of her pain, it's baffling that we're still meant to see her as in the right at all.