Quote:
Originally Posted by
Snape'sGirlThru&Thru 
I think they're still considered Half-blood because they would have "Muggle blood," so to speak, in their lineage because their grandparents on their Muggle-born parent's side are Muggles. To be considered Pureblood, the child should have no direct Muggle ancestors (i.e. parents, grandparents, great-grandparents, etc.). I don't think it's based only on whether the parents are magical or not.
I think only prejudiced Purebloods who actually care about bloodline and lineage and all that would think that. Most other wizards and witches who don't care about that kind of thing aren't inclined to think any bloodline is "better" than other one.
One thing I wonder about though is what a child with a Squib parent would be. Like if a Squib married a Pureblood. Would the child still be Pureblood? Or Half-blood? Or if a Squib married a Muggle. Is the child a Half-blood or a Muggle-born?
I agree with that. My dad's muggleborn, and my mum's pureblood, and my brothers and I are considered mixed-blood, but not half-blood because both of our parents are magic. I think a squib's children would be considered half-blood, whomever they married. They're from magical lineage, so calling their children muggleborn if their other parent was a muggle wouldn't be correct, but if their other parent was a witch or wizard, that wouldn't make them pureblood. But, like you said, no bloodline is better than any other.