Also, I've found, temperature can have a huge influence. I like to do winter camping in the middle of nowhere in the mountains. I was surprised to discover that when I'm in freezing conditions like that, I simply won't feel thirsty -- apparently ever -- so I set a timer to remind me to drink.

I learned this the hard way on the third day of my first such trip, when my urine had become brown due to dehydration.

It is probably best to follow real information then.

Note that while your thirst response may be declining as you age, mine hasn't.

Annicdodes aren't data, mine or yours.

IMHO the 8x8 myth may or may not be optimal guidelines for you as they aren't based on anything but rumors.

It's not just aging that makes us bad at noticing when we're dehydrated. The ubiquity of so many types of foods has given us the ability to satisfy the craving for that which stimulates our senses, not necessarily what we need.

I know this is anecdotal, but I've heard so many people tell me that they skip meals because they simply "forgot to eat." Do you think those people remembered to drink water? I don't think so.

So, yes, people tend to be terrible at noticing what they need, and when they do notice they are terrible about doing something about it.

Which is both true, but also irrelevant for 99% of the people for 99% of the time.