My biggest personal no-no in general for inflation/transformation is the kind where characters are sad to the point of tears - so if there's like... genuine crying, sadness, distress, it's hard for me to not get upset myself. Although, when it's given a funny or cartoony angle that clearly shows it's not serious emotional turmoil, it wraps around to being enjoyable for me again!

I also don't really enjoy identity death in transformation in general, and since something like berry, especially permaberry stuff, would count under that, it's ideally not something that entirely erases any aspect of a person's life or treatment as "human." Really, the biggest draw to something like perma is when it gradually becomes more and more casual for the inflatee, adapting and getting used to it~ I'd like there to not be "well, my entire life is ruined" although having some shake-ups the character needs to get used to is nice. Like "oh, I can't be athletic anymore, but I've found a new competition I can engage in" that kind of silver lining. Having other characters being in on it, and being supportive helps even more.

Like, permaberry stuff where a character goes for regular juicing appointments to get smaller again, only to inevitably swell up to a helpless orb after a week or so, is really comfy and cute~

Although the funny reactions of passersby when you get into inconvenient scenarios is, very fun :3