I agree that when gigs come in, many look like this, and they will be sold in this condition. Without the proper knowledge or care it will die in approximately 1 month. See the sticky at the top called
"Protocol for using Ciprofloxacin to treat infected anemones."
I say it's unhealthy because of the following traits:
1. Exposed siphonoglyphs (rabbit teeth looking appendages coming out of the mouth). Healthy gigs RARELY have them exposed, even after feeding. I've had my gig for over a year and have only seen it a couple of times.
2. Overall even tone, pastel color. While it actually looks nice in terms of color, this is very deceiving because it masks the fact that it's lacking any brown color, which indicates a healthy zooxanthellae population. It could be that the photo is over-saturated to the point that the brown is just blasted out.
3. Short tentacles, looking more like haddoni than gigantea. Even newly acclimated gigs have tentacles longer than this one. I had a purple gig that actually looked fine for two weeks, then started dying. Even if the lights were just turned on, gigs tend to have tentacles that are longer. My gig is about 3/4 of the size at night than it is during the day, but the tentacles NEVER contract to the size of haddoni. They do get shorter and appear less "inflated" but not to the point of me calling the tentacles "shriveled" and I would never describe them as bulbous.
Granted, this particular specimen looks better than others I have seen, and those have survived. If you plan to purchase it, I would do so very cautiously and plan to have Cipro on hand when you receive it.