I don't think things need scotchguarding any more Firsttime. Last time we had our sofas recovered we were told it was unnecessary and the same with the recently bought carpets (from John Lewis) Our sofas are quite patterned so don't show marks, apart from the arms which get grubby, but clean up quite well when done by our regular carpet cleaning man. The carpets clean well with washing up liquid apart, that is, from the bit when DS1 dropped a tin of dark green paint and even that is only noticeable if you are looking for it! 
I should add that although we haven't had a dog for a couple of years we have lots of grandchildren and a couple of cats! 