I think coke is just one of those drugs that affects everyone differently. The first time I did it, I snorted about a 1/4gram all at once and didn't get much from it, just more talkative and a pounding heart. We did some more and went through about 2-3 g between 3 people in about an hour or two. I did feel a little euphoria after I did some more but the other guys were REALLY enjoying themselves. They were both sweating like crazy and talking about nothing as fast as their mouths could move. When it was all gone, they turned into the typical coke fiends, but I didn't really care for more. I went home and it took like 3 more hours for me to fall asleep.
But the second time, I got some better quality coke (I guess) with a bunch of cokeheads I worked with (it was a party where basically everyone had a sack of yayo on them for personal use). I was just doing key bumps and got higher than I did off of the lines before. Go figure. Even still, it has too many side effects for me (headaches, pounding heart, irritable-as-shit when it wears off, etc).
If you aren't getting high off of those keybumps, your natural instinct should tell you to do some fat lines and see if it is totally bunk or not.