For example, a jar of Jalapenos, product photo: https://i.imgur.com/mprWr6R.jpg
In reality, the jar's cross-section isn't circular as it appears, it's an ellipse/oval: https://i.imgur.com/dXDUOR9.png
Only the first photo was included in the item listing. When the groceries were delivered and I pulled out the jar, I was so surprised by the odd football-like shape that I couldn’t stop laughing for a few minutes at how well they’d fooled me.
Another common thing to see is familiar product packaging that is just “scaled down”. Everything about the packaging looks the same or very similar, but smaller - especially fonts. This deceives the eye into believing the product is much larger. I recently fell for this when shopping for some conditioner. The packaging is not exactly the same but close enough to fool me at a glance:
What I bought: https://i.imgur.com/MdAuhS0.png
What I expected: https://i.imgur.com/MGxdD0d.png
I'm inclined the believe this is on purpose because in real life, the fonts are way too small to read comfortably. If not trying to mislead, I would expect the packaging to be designed to be legible, right?
It's especially frustrating because I usually would've just paid more for the larger size.