You'd be totally wrong.

It's a bit thin and watery, and the taste isn't very strong. But it is slightly sweet.

Source: used to breed pet rats, and mama rats leak sometimes. No reason to not taste it when that happens.

Wasn't yummy, but it wasn't bad either.

And, yes, I'm certain it was milk and not urine.

Hell, our neighborhood had a cat back when I was a kid. Not a stray, but not anyone's cat either. She was super sweet, loved kids, but did not love being in houses. But she did love our back porch for birthing. And she was perfectly fine with any of us handling the kittens, and loved belly rubs while producing milk. So, it was inevitable to end up tasting it if you were an adventurous kid that knew where the milk in the fridge came from because you'd milked cows before.

Most milk tastes roughly the same tbh. We've bred cows and some goats to where they're different, but the taste varies more by diet than animal. Mind you, I haven't gone around sampling everything, but I don't have an artificial mental block about tasting it either, and I've been around a lot of livestock and pets that were lactating over the years.

Fat content is the real, major factor after diet.

Carnivores, or omnivores that eat a lot of meat, tend to be a little "gamy" compared to herbivores. Goats are an exception, but the ones I've had "from the tap" so to speak, were bred for milk, so weren't as gamy as it can get.

Horse milk is pretty funky. Not bad, but I wouldn't pour a glass either.

Trying to think of anything that stood out from the herd, so to speak, but nothing comes to mind beyond that.

Have you ever met the kind of people that keep rats as pets? I'm gonna guess that at least 1% of them have tasted rat milk.

There have been studies on rat milk, which itself suggests that someone has developed a process to extract it. I think if you spend sufficient time thinking about how to extract milk from rats, and you have no interest in drinking it, it'd be weirder than the alternative.