it's part tires, but a rough reaction to potholes doesn't mean it's a shit suspension, it means that the dampers are stiff, which for some people is a good thing.

the best way to tell if it's an aftermarket susp or cut springs is to look inside the wheelwell, and look at the actual springs. are they a different color (aka not black with road dust, and powdercoated red or something like that. the shock will prob be a diff color too like white as opposed to grey or black)? also a cheap suspension would probably bounce around, as opposed to react stiffly to road imperfections.