The realities of TV production conflict with the realities of manned space flight, but at least the producers have tried to give us logical explanations for why we can't have true zero G effects shots every time we see the crew. I would guess the hairspray needed for a six year mission takes much less room than the amount of booze consumed by Adama and Tigh in the 4th season of BSG.
There is nothing logical about magnetic hairspray. Even aside from the fact that there's no practical benefit to making your hair behave as if it has weight when it actually doesn't, all those tiny magnetic particles would get into the equipment and short out the systems and kill everybody. It's not just unnecessary, it's an insanely bad idea.
What they should've done was just cut everyone's hair short, or at least have the actresses wear their hair in tight buns while in the "weightless" parts of the ship. What they've done is to put glamour over good sense.
When all is said and done, this is a TV show, and glamour will always win out over good sense. I stand by my earlier kudos to the writers trying to balance the obvious limitations of a serialized TV show with the realities of space travel.
On an unrelated note, I just read Ex Machina last month. I liked the follow up to FTWIHAIHTTS, and it was a nice peek into the lives of the TMP crew. Thanks for the ride.