Hmm, yes and no.
I really like what Pent said... I agree with most of it (particularly with the last bit... "rares" are the most common pets these days! If you truly want a rare pet you're better off looking at lowbie level unusual skins imo haha). I've camped for many a rare and decided after a few days that I just don't like them.
Here's the bit I'll probably get raged for.
At the end of the day... it's your choice to camp. Madexx is exactly the same as every other scorpid... he just looks different. Heck, there are better tenacity (tanking) pets than scorpids, and his family skill is shared with another family... That's a fair bit of choice. If you decide that you absolutely must have that skin, either a) you're camping for vanity reasons alone or b) you don't really "need" the pet, you just want it (otherwise you'd have tamed an easier alternative). Same can be said for Sambas... plenty of cats, hey, even just lions - it's your choice to camp that particular skin. Skins are like ... titles, or mounts, or tabards. They're an added bonus, you don't need them, and to have them is in a way like showing off how YOU were lucky or YOU had the time to do this or YOU put in the effort and not everyone else has.
That's my personal... issue with the whole "rare camps are too hard" debate. I think Madexx spawn timers are fine, however I do agree that the RNG of the situation could benefit from being tweaked a little. Selfishly, no, I don't want to see every random person running around with TLPD or something because it has a two hour respawn rate. I like to see other hunters with camped pets, I usually try to say hi or give the pet a hug or something because it's neat to see that someone else (probably) put the time in to get it also.
What I don't like is that putting the time in doesn't guarantee you the spawn. But there's not much to do about that.
Of those options, I'd say either keep them as they are or shorten them slightly (though not drastically)... for example, maybe 6-16 instead of 6-24, or perhaps reducing the number of spawn points (or increasing spawn rates depending on the number of spawn points... eg Arcturis still having a 24ish hour spawn timer, while Karoma or Madexx would have a 6-10 hour one). I don't know. I don't think the solution is just to cut down spawn timers to nothing (or as good as), because yeah, camping is a part of deciding that you want that special skin and no other skin will do. It gives people goals to achieve... which for me is probably the reason why I camped pretty much every tamable NR and Cata rare ingame (even though very few remain in my stables). It gave me a goal, something to do, and a bit of a buzz when it was achieved. ^^
Just my feelings on the issue, either way I'll learn to live with whatever Blizz gives us, but personally I'm not overly bothered by spawn timers as they are, having camped many pets and mounts with plans to do more in the near future (alt almost high enough eee!).
Edit: Also, as for the "it's unhealthy" argument... you are in charge of your own life and health, and if you're silly enough to sit in front of a computer all day every day camping some pixels, that's your problem, not that of the game! The game is here to make money, keep people entertained and keep subscription up, not worry about personal health issues haha. I repeat... it's only a pretty colour, you get equal elsewhere, it's your choice to sit in front of the computer and get unhealthy or whatever. Yours... no one else's x_x