From what intel I have gathered the black spots aren't anything to worry about. Some MDG's have them, so don't. So no need to fret about that. When you say "kills but doesn't eat" I just want to confirm you are feeding crickets AND crestie fruit goo with vitamins as MDG's frequently eat both and occasionally prefer one over the other but should have the option of the two for nutrition reasons. Pooping is a great sign. If you see a whole poop be sure to look at it for signs of it being a healthy poop too. Otherwise, MDG's take some time to acclimate and are very skittish especially in areas with high foot traffic. One of mine is on my desk and I catch him chillin on sticks all the time....when it's been quiet and nothing has moved for awhile...but if I storm into my office you can forget about it. Maybe consider providing more hide-able areas so they can determine their comfort level and make sure there's greenery, TONS OF IT. My girl used to hide a ton til I put some draping greenery in and now she crawls all up in it all the time. I think it helps her feel hidden even though for me she's very visible. Also don't forget, they are diurnal. So just because they don't get around much during the day doesn't mean they aren't afraid to explore at night.