how many/what species do you have?
I would say this is normal, from your pictures. she's not unable to hold her tail up (as in the 4th pic). they are not stiff, but bendy and somewhat prehensile, with extra sticky setae on the end.
some crestie people talk about FTS, or "floppy tail syndrome". some people think it's a "real" condition and some people don't, but if it is real it is thought to be associated with low calcium when young. however, it is decidedly not MBD. some people also hypothesize that it's caused when cresties perch upside down a lot. there's quite a bit of debate on this topic.
anyways, I think it looks normal. she's pretty, by the way. does she fire up red?