The potheads I've known over the years, the ones that aren't just smoking and enjoying it, but the ones that make smoking weed their identity, there's a degree of realism to the generated image.
That kind of pothead tends to reject the idea of dressing to conform to societal expectations, and just wear what's comfortable. They'll tend to keep snack foods around, and that will be the majority of their intake. They'll have perennially bloodshot eyes and goofy grins on their face more often than not.
And, when possible, they will buy giant bags of weed. Perhaps not as giant in proportions as the image has, but I've known people that buy by the pound rather than waste time with small quantities.
The image is definitely exaggerated, particularly the face of the figurine, but I've known a few dudes that look enough like that to make it even funnier. That kind of shit-eating grin and the impression that they're looking at another world while they're right in front of you.
Even the stringy, greasy looking hair is something you'll see on the lifestyle potheads sometimes because they lose track of time.
But the image in its entirety is a bit exaggerated. It's a cartoon version of a lifestyle pothead, kinda like the Cheech & Chong movies lol.