Former President Donald Trump hawked his new Trump-branded sneakers at “Sneaker Con,” a gathering that bills itself as the “The Greatest Sneaker Show On Earth!”.
That's one thing, another thing is that he did it as a president in the White House. Republicans talked about Obama wearing a tan suit or doing "late salute", was disrespectful to the office of the president.
In this instance he was outright using the office of the president to advertise a commercial product.
I don't think there is another US president that did something equally cheap.
In fact I don't think there is any other president that was using their office to advertise a product like that.