The location of the toilet isn't an issue...it sounds like you may have other problems with the drain line. Does the stuff get out of the toilet, but not flow? Or, does it just swirl around? If you take say a 5-gallon bucket and dump it into the toilet, does it all go down? When it was installed, the wax ring could have slipped and be blocking a good portion of the flange. Somebody could have tried to flush a toothbrush, or something else down the thing. I'd pull it up and verify there's no problems both within and downstream before blaming the toilet.
It makes no difference the type of toilet or the location, but the condition of the install and the drain line will make a huge difference.