acrylic craft paint clots

[so-gracefully.livejournal.com]

i have this issue with my acrylic craft paints (they are the very cheap kind--apple barrel brand, in bottles), where they get these stringy chunks of dried paint inside the bottles, kind of floating around inside the still usable, wet paint. does this happen with all bottled acrylic paint, or would it not happen if i got a higher quality paint?