Dating methods

So, based on scientific studies, which dating methods are or are not reliable? Can you really find out the age of something when you don't know what it has been through? Give me your thoughts. OH, and don't forget, everything you give me needs to backed up with sources to prove it. I look forward to seeing what you say...

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Miss Smartie Pants Yes Um

First, have you personally ever dated something using the scientific procedure? Next, how can you tell if you followed the "right procedure"? It's like any experiment, you may think you correctly followed it, but didn't.
If there was an ice cube sitting in a small pool of water, could you tell me how long the ice cube was sitting there or how big it initially was? My guess is that you could "scientifically" figure it out, but never know the truth. Unless, of course, you were there when it was set out.

But can you really put it in the same time frame? Can you say that an ice cube the size of a 1in cube was there when something else happened, when for all you know, that ice cube may have been sitting there since it was a 1ft cube and also going through weather to get to the point where it was at now.