@Smitty1991  
If you got a weird fetish, then it’s not that big a deal, so it’s probably better to not be judgmental about people who do.
 
But some people are way too into their fetish, don’t take it in moderation, and it comes to dominate their life. Those people - or rather, obsessing over one particular thing in general, should generally be frowned upon. Unless perhaps that one thing is something really beneficial to the world like being obsessed with practicing your skill at surgery or science. Though even those kinds of things can go too far for a happy and fulfilling life.
 
But even if Pinkie wore diapers every night and sucked on a pacifier, as long as she never has some issue because of it then it’s fine. But “weird” things like that often tie to serious issues. They could lead to a degradation of self-worth, self-confidence, or self-respect. It could get out of control, or become the only thing she looks forward to, growing into a large obsession. She could use it as a crutch for dealing with some other issues she needs to confront instead of hiding from.
 
When it comes to atypical behavior, there tends to be a lot of co-morbidities - other issues that usually relate in some way (such as are caused by, cause, or have some shared cause). This is actually kind of visible even in bronies in general, with higher rates of depression, anxiety, autism, gender dysphoria, etc. Not to say infatilism or bronydome are bad by themselves, only that they often share some poor company (co-morbidities), ie, may either cause, be caused by, or have the same cause as real issues.
 
Sorry, it’s 240 am and I just finished rambling on about psychology in my last comment elsewhere so I’m waxing rambly and verbose Xp
 
All that to say, don’t be one of those people who go around with absolutely zero self-awareness asking SFW artists for fetish art, because you don’t know how to take things in moderation, and are so obsessed with a fetish that you’ve lost (or more likely never had, but probably because the fetish kept you from developing it either by distracting you or serving as a crutch) the ability to interact with people in a cordial and level way that does anything better than make them immensely uncomfortable.
 
That is what I meant by “the ones who are way too into it and don’t know how to take things in moderation…”. Well, that, and the ones who let some particular thing swallow their lives :p
 
Honestly I’m probably talking about myself, here, with ponies…

@Cirrus Light  

 
Care to tell me more? I’m afraid I don’t know what you mean!

Yes, Pinkie, you can explain, but many of us here already know what “adult foals” and “infantilism” are, and most, I think, won’t judge ya for it (the ones you really need to watch out for are probably the ones who are way too into it and don’t know how to take things in moderation… :p )

@MrSeveryn  
But nopony can know Pinkie’s secret. Nopony! Not even… Rainbow Dash’s house.

@MrSeveryn  
Brain shorts out

@Brony_Conundrum  
I HEARD THAT!!!

@T-storm Berzerker  
Pinkie forgot the best thing about a secret is secretly telling someone that secret, therefore adding to their secret collection of secrets. Secretly.

I’m practicing my Maggie Simpson cosplay.

@Brony_Conundrum  
HOOPLA!

“i just popped a molly, that’s it! nothing unseemly going on here.”

It’s candy!

This is a load of barnacles…