1. Imposter's Home For, Um... Make 'Em Up Pals ~ A vile and traumatic mess. A callous insult to Frankie and her fans. A complete disgrace to Foster's.
2. Where There's A Wilt There's A Way ~ Just like "Imposter's"--same writer, same long-winded title, same unwarranted cruel treatment of sympathetic and beloved characters.
3. Foster's Goes To Europe ~ Basically a mish-mash of inconsistent scenes and gags assembled together under a very basic premise... up until the ending, which is brutally coldblooded and absolutely disgraceful on part of the entire crew. Eurotrish was an entertaining one-shot character, and the fact she manages to return home might be considered as the saving grace--except she gets cynically mocked and rejected in the ending credits. Yes, they definitely weren't trying to hurt people's feelings...
4. I Only Have Surprise For You ~ The meanspirited nature of this episode took a while to kick in for me, but once it did, it stung pretty badly. Like with the other listed episodes, the writers completely misunderstand conflict and making characters "suffer for their art". It's funny to see the egocentric, larger-than-life Looney Tunes cast endure extreme physical pain--but it is NOT funny to see a sympathetic and wholesome kid like Mac become psychologically traumatized over what should be a day of joy and happiness.
5. Phone Home - This had a very promising storyline and setup -- Bloo envying Wilt and his heroic achievements -- that really deserved it's own half-hour episode. Ironically, though, it didn't even bother to make proper use of it's 11-minute runtime, as it derailed with the annoyingly obvious saga of Cell Phone Guy. The Groucho Marx chicken was cool, at least.
Additionally, I find it almost impossible to get into any episode in which Frankie is absent or only makes a blink-and-miss-it background appearance("The Big Leblooski", "Eddie Monster", "One False Movie", "Infernal Slumber" and "Make-Believe It Or Not"). They definitely aren't bad episodes because of it, but for me at least, the show loses a lot of color and warmth without Frankie.