When something smells like bull(shit), you have a feeling it's not true.

"Smells Like Bull" - printed on a girls sweatshirt, next to a picture of Teddy Bear - https://www.zumiez.com/new-girl-order-smells-like-bull-crewneck-sweatshirt.html
What on earth does this mean here?

Exactly what I wrote upstairs...

When something smells like bull(shit), you have a feeling it's not true.

Похоже на вранье/брехню
https://en.wikipedia.org/wiki/Bullshit
https://ru.wikipedia.org/wiki/Брехня

Exactly what I wrote upstairs...

я не понимаю... При чем здесь Teddy Bear?

Because when you look at the shirt and see a teddy bear smelling flowers, you expect it to be a sweet, cute message, and instead you get “smells like bull(shit)”

Нет, мне этот юмор не понять. Хотя, я не заметил что он нюхает цветы - это добавляет немного смысла.

It’s just a gag shirt. No my kind of humor either, but there it is))

But leaving the shirt aside, the expression SMELLS LIKE BULL means that you’re not buying what someone is telling you... it seems like bullshit to you. It smells fishy.

BULL is a euphemism for BULLSHIT - we use them interchangeably. If you correct it, you’ll send the message that BULL is incorrect.