It would be valid to ask why meat tastes meaty, if you are talking about the red meats it has something to do with the blood, since the ‘juice’ that comes out of the meat during cooking is very meaty in taste. But then again there is the fact that meat stock needs bones in the preparation to be good, but this may be due to the gelatin and similar in the bones that gives stock a good consistency.
If you are realy interested why meat tastes meaty, please open a GQ thread on the subject, I’m sure Mangetout would be able to help answer that question better than I.
AAAHHHH!!! I use this in my lab sometimes (for protein crystallizations), I was extremely upset one day when I actually got crystals in it, which meant I would be using it more frequently. The stuff is horrible - so bad that I’ll wear double gloves before even touching the bottle, and throw them away immediatly.
Spermidine is another chemical I use with an interesting smell, but I won’t go into what it smells like 
I was under the impression that phosphine was the compound responsible for “fishy” smells, and that trimethylamine has more of a prawn smell. Got this out of a book (Merck Index?) which I don’t have with me and can’t cite.