nook said:
I remember that if you hack, you have a "virus" and whoever interacts with you will be given the "virus" and can spread and vice versa.
That's the biggest lie I've ever heard. The program most commonly used for modifying save files in Animal Crossing: City Folk doesn't do anything malicious to the user's game or computer, and visiting a modified town will have no impact on you.
A "hacked" town is just a regular town except the user has specified what acre types are in what position, what buildings are in what position, and what items and objects are in the town, and what positions they are in.
I'll say again:
there is no negative impact from visiting a town which has been modified using 3rd party software.