[TazeTSchnitzel]

The thing to do is check how the trademark owner feels. I believe Visa and MasterCard are fine with using their logos to show they're accepted (those stickers every store has are surely legal?), but remember that Microsoft don't let you use the word Windows in a product name, except in the form "for Windows".

[wavefunction]

These firms all have brand guidelines which are certainly not being followed/adhered to by this font. It's a nice effort but not a good idea to use in anything public.

[michaelmior]

I think those stickers every store has are distributed by the Visa and Mastercard (or some vendor who has a direct association with them). In any case, it seems like a different situation if the source of the material is ultimately the business itself. In the case of this post, it's a third party with no formal association making use of the logo.