I never feel thirsty, can't remember a time when I've ever felt " thirsty."
On occasions I do tend to always feel hungry and apparently always feeling hungy, especially soon after eating, is a sign of dehydration and our bodies, especially mine, misunderstanding the signals.
The colon normally absorbs fluid so once removed, we need to consume more fluids to compensate and also replenished our electrolytes.
For myself and some forum member, drinking when feeling thirsty, it's not as clear cut as that; I found dehydration crept up on me, I begin to feel tired and before I knew it, I found myself unable to stay awake and I lacked the motivation to actually get up an make a drink.
Once I've dehydrated to such an extend I need more than just fluids, I need to replenish my electrolytes too.