I have primarily 1/43 scale cars. But that varies greatly even from the same manufacturer. I would suggest taking a miniature with you to the store or use some other scale identifier (ruler, printed out silhouette, etc.). Even the large scaled 1/43 cars are not that bad, it is just more noticeable when a smaller and larger scaled are side by side. Unfortunatley if you cannot check them out in person first it is just a roll of the dice.
Also if the 28mm figures are on slotted bases the extra height helps make things look visually ok, even though 1/43 is technically larger than it should be.