I actually would disagree with this almost entirely.
For one, Seneca is very sketchy -- often more so than Anderson. You've to remember both these towns are basically shopping areas, anderson more so than Seneca (seneca is more of a dying/older economic center, where as Anderson is still growing) Most houses you find listed for cheap online are going to be in the less than favorable areas, too.
Clemson is very family friendly if you know the right areas. My father in law works at Clemson, so my husband and his siblings grew up here. If you want somwhere cheap to live, there are places (dependent upon your definition of cheap) within the town, away from students. If you need any help in that regard, feel free to message me.
Personally I love Clemson. It is a bit overwhelming being around SO MANY students sometimes, since the town is here because of the university. Still, you are close enough to Seneca, Anderson, and Greenville that it's easy to get away from them, and enough to do. Besides, the student body as a whole relatively friendly.