I've downloaded stuff from the exchange (I also upload lots and sims) and it was fine- yes you can get badly constructed stuff or you can get stuff that was created using non-EA CCs or EP/SPs that you don't have and then the file won't work or something will be broken with it. Sometimes the creator will include a link in the exchange description outlining if something was used outside the standard EA generated content and where you can get it. It's also somewhat easy to see if a sim or lot or clothes or whatever includes something out of the ordinary. The file will be huge! If 99 out of a hundred standard everyday sims have a file size around 1mb and the sim you are looking at has a file size of 50mb then something extra is there. Lots, clothes, furniture are the same. Look around and see what seems standard size wise and avoid anything ridiculously larger on the exchange if you need peace of mind about it.
