Polka Dots, Peplum and Hearts.

This week it's been pointed out on every blog (even the home decor blogs!) that Old Navy has an inexpensive version (Rip-off?  Knock-off?  Replica?  what is the politically correct term for this?) of this Alice + Olivia sweater:

Old Navy's less expensive (and non-sequin) version:

Forever21, not wanting to feel left out, also knocked-off last years' uber-popular - even I bought it - J. Crew original (available this fall in a lighter-weight Merino wool) :

Forever21's version:

Old Navy's version:

Now, polka dot sweaters?  Over-sized Graphics? I don't know that I feel like a designer or brand can really trademark that.......

Looking for a different version of polka dots?  I love this peplum polka-dot top (say that quickly, three times.)

What do you think of mass retailers' ripping-off/knocking-off/replicating designer's ideas?