Many times, frogs will look dull before they molt. After shedding, they look beautiful and you breath a sigh of relief. Temperature, humidity and other issues can affect color, as well. Also, Cranwell's horned frogs will change color as they mature (usually more dull)...
Not meaning to disagree with the previous posters, but nightcrawlers are soft and pose no impaction risk IMHO. I don't worry about the usual rules regarding size of feeders when feeding nightcrawlers to pacman's - my guys all eat/ate worms much longer than they with no apparent ill effects. Obviously, this is just for nightcrawlers...