You've been praying to the Pony Gods, right?  That's step one.  It's very important in receiving pony luck.  I suggest making small offerings of MLP combs and brushes at your nearest Pony temple.

When you do get pony luck, it is wise to thank the Pony Gods for their prosperous bounty.

Definitely looks like a rehair.  Pony collectors seem to frequently add a lot length when rehairing.  It also looks quite shiny which also suggests new hair.

X-eevee's daughter is named Lily after the flutter pony.  She got the pony MIB around the time she was born I believe.  For her first birthday I painted a canvas with Lily on it. She told me that if they had a boy he would be DJ after the Dance n Prance pony.

Spike hasn't be mentioned yet.

Clarissa from Clarissa Explains it All is legitimately my idol.  I adored her as a kid and still do.  I've contemplated making a cross stitch sampler with "what would Clarissa Darling do?" on it.

Are You Afraid of the Dark is second.  My friend and I watch episodes in the dark on Halloween.

Kenan and Kel are my third place but honourable mentions to Alex Mack and Pete and Pete.
 
On a related note,
"Welcome to Good Burger, home of the Good Burger, can I take your order?"

I bought a large lot of ponies which included the saddest looking baby pony I've ever seen. Baby Blossom's hairline was completely split down each row so her hair was hanging out loose but still glued together in rows. Her whole skull was open. I had to do some extensive fimo moulding to connect her head back together then managed to rehair her but she can only ever wear her hair in stratigically placed pigtails to cover the clay. I eventually upgraded to a better one but haven't managed to find anyone willing to adopt her. I think I may move her to my desk so she can be appreciated for overcoming her traumatic former life.

CLR is a cleaning solution that removes calcium, lime and rust (hence the acronym). Any kind of rust cleaner at a hardware store should work the same.

If a pony is dirty beyond what will come off with a few swipes on a magic eraser, it is more often than not dirty on the inside too. Any kind of dingy shadow on a pony is a sign that all is not well inside. White and pale yellow ponies tend to show this best. Ponies that have clearly lived eventfully lives with children 9/10 have something internal as well. I've seen some pretty foul ponies and many of them looked ok outside.

As for value, I don't think I've ever seen anyone reduce the price on a pony simply because the head is loose. And if they are, it wouldn't be by much. If I sold a pony with a loose head seam, I would mention it in the description, especially if it's a pony I've personally opened up. I don't think it makes it significantly less mint. If a head comes off easily, it's better to know for sure rather than discovering a year later that she's been degrading inside. I would only second guess this if the head is so difficult to remove that cutting the seam is necessary.

As for water getting inside during cleaning, you absolutely must tilt the pony so the tail is lower. Always alter the position during drying. I tend to wait at least two days before displaying the pony. I've had a g3 sit drying for a week with the head off and still discovered she had water in her feet.