Never eaten Vegemite.
We used to tell the new American and Canadian students at uni hall that the Vegemite at the breakfast bar was chocolate spread. Canadians usually found it funny, if not gross. Americans didn't tend to appreciate it much.
When I worked at a US hospital with another Aussie we kept a large jar of Vegemite in the tea room fridge. A Romanian girl thought it was bad, I explained it was eaten on toast & kids loved it. Someone else asked what it was, she said with a look of complete disgust "they feed it to children" like it was some form of child abuse.