One of the most common mistakes is delimiter in a field. E.g. comma as thousand separator...
> 100,1,200,300,10,100
You suspect that an in-field comma is causing a split where there shouldn't be, but who's to say which number got split up? 1200 into 1,200, or was it 200300 to 200,300, or 10100 to 10,100?