in my eyes line breeding is sometimes a good thing when done right father - daughter - grandaughter and great granddaughter and the same with mother -- son and so on
Dexter,
I line breed my hounds, but from the statement above that is a case of inbreeding. I think most out there don't truely know the difference in the two.
As for the original question, if you choose to closely linebreed, you had better make for darn sure what you start with is exactly what you hope to reproduce. As, close linebreeding multiplies both the positives and negatives of said line. It is not uncommon to see traits of ancestors 3 generations back surface if continued line breeding occurs. The foundation of your breeding program needs to be based on for sure real deal dogs if you elect to breed tightly. JMO!!!!!!!!