In the case of Basic Maths, there's examples of it on the designer's own demo page, depending on your browser settings.

Some people might say this is the user's fault for overriding the original font choices.

I'd say not all fonts are pleasant to read on all machines (except Macs where they generally all come out nice), and expecting the user to stick with ugly aliased ones for the sake of your layout is unprofessional :-P