Dumping small amount of cigarette ashes into the beers , people say it helps give the beer an extra "kick"...
how far this myth is true..
Adding any particulate to a beer will reduce the carbonation due to more nucleation sites and the flavor may change from the tobacco ash, but the only way to increase the alcohol content of a beer in your glass is to add alcohol.
I would suggest the extra kick would be due to the fact that as you smoke the cigarette, you are taking in nicotine, which does enhance the effect of alcohol. So the effect is not coming from the ash, but the cigarette you smoke to get the ash.
I heard this from someone in 1993 and his explanation was it changes the boiling point (which still didn't explain how it made the beer stronger).
As happy as the above comments may make you, ashes in your beer is not a big deal and frankly, I'm amazed at the question. I tried your experiment of adding cigarette ashes into my coffee. I have to say I was disappointed. Besides seeing the happiness on the faces around me, I can't say it made any difference in the taste. Now beer on the other hand may have a more profound taste change due to the ashes. It really depends on the kind of beer and the type of ashes. However, I do believe that if you like beer you might not even notice the ashes. For example, if I'm looking into a beer glass and something is floating inside, I would be surprised to even notice it. From the point of view of the ashes. I can only surmise that they would prefer to go into an ash tray.
Answer: no, there is no change in taste in small amounts of ashes. The more ashes you add to the beer the more of a scratchy texture but no difference in taste. If you fill the whole beer with ashes you might find it milk shake like but bitter. If you ever try that I'd like to hear your experirences.
I am pretty sure it gives you a kick but I don't think it's the one you are thinking of. I am interested in a more experienced answer because I went to a rural area near a village in a Mediterranean country recently and they told me to watch out because guys in that area spike girls' drinks with cigarrette ashes so that they can get them more drunk or make them wanna puke so that they both 1) make fun of them and 2) can take advantage of them. And there were some known solid incidents from the girls I met not just rumors so I'd say it does a good damn job. I came across this because I'm looking for a way to avoid drinking something like that because that sounds like a freaking dangerous trap, but I can't find much.