Exactly my point. The propylene glycol within the solution is probably OK because it is a very small percent of the total solution. The problem starts when the accompanying ingredients (water & alcohol) evaporate, thus leaving a strong residue of propylene glycol on the floor. It can be absorbed through paws and/or licked off of the floor. Remember that dogs & cats are smaller than humans, so are potentially affected more adversely by toxic substances.
Hills (Science Diet folks) use ethoxyquin as a preservative in their kibble. Ethoxyquin is a potent carcinogen. Hills claims that the minute amount used won't harm animals. Oddly enough, ethoxyquin is also used in their prescription diets - foods used for sick animals. Now, why would you add a carcinogen to a food & feed it to a dog with a compromised immune system or other organic problems...?I digress....
Regarding Snopes, etc., I cannot believe most of those websites. Unfortunately, the internet is full of misinformation. That's why I went directly to a guy who knows his chemicals.
Bottom line - why chance it? There are natural cleaners available that are not harmful to animals or the environment. I have a German Shepherd whose paws bring in more dirt than a front loading tractor. I find that vacuuming & wet mopping with water only (I have tile) works just fine. I'd rather have slightly discolored grout and a healthy dog & cat. Just my opinion.