Elections are a farcespeaking for the topic
The electoral college method of electing US presidents has certainly added to the general perception that we are not doing very well in this arena. The electoral college was developed before rapid means of communication and travel were available, and was the Founding Fathers' alternative to having Congress elect the president - imagine where we would be right now with that scenario! However, its existence means that the president is not truly elected by the people, and of course cases like the Bush/Gore election occur from time to time to remind us that winning a majority of the popular vote may not be enough to put someone into the White House. Unfortunately when this happens voters feel disenfranchised, and fewer of them vote the next time around.
I think it's human nature that we only complain and act when we are angry with our politicians, and few people participate when things are moving along smoothly. The election process has not changed much over the years, but people's perception of it has.
I freely admit that teaching Civics in an age when politics has become so partisan and bitter, and when money has such a dominant role in the outcome of races (perhaps only rivaled in this country by the Gilded Age), it is sometimes difficult to teach the Constitutional ideals of democracy when I am not sure they are still intact.
I do still believe in this system, at least as far as Winston Churchill did when he famously said:
It has been said that democracy is the worst form of government except all the others that have been tried.
and in his opinion of the average participant in elections:
The best argument against democracy is a five-minute conversation with the average voter.
but I also remember that there were times such as the 1790s and the 1860s, when it seemed all was lost and partisan politics would be the death of us. And it clearly was not.
Besides the electoral college scenario in the post above, which I think really makes American voters feel helpless in their choice for president, there are a few other factors (in US society at least) which may support this idea.
Many feel it's the media that decides who we should vote for. By presenting certain candidates in a good or poor light, reporters can influence public opinion toward or away from a candidate for office.
The other piece of evidence that might be strong for you is voter fraud. In every election you hear reports of someone's dead grandma having voted for a certain politician. This certainly doesn't build confidence in the system.
This would depend so much upon what country you are talking about.
In the US, this would be hard to argue, though you could. You could say that all people running for election are concerned only with getting and keeping power for themselves, not with what is best for the people. I suppose you could also argue that money dominates elections and that the people don't really get to decide. Both of these are very cynical views.
In some other countries, it would be much easier to make this claim. An example that comes to mind is Russia, where Putin's party only allows as much opposition as it wishes to have.
If arguing for the farcical nature of elections, you might say that only individuals who successfully work within the party machinery a have some degree of party approval stand for qualification to run political office. As a result the electorate must choose between pre-selected and pre-approved candidates so that in the case of any winner, there is already a party loyalty and party approval and an ongoing relationship within the political machinery.
There was a time in the distant past when many politicians were worthy of admiration and respect in the United States. Those days have certainly passed, and most politicians these days--be they local or national--are out for the power that can be gained from holding political office. Until political parties stop putting their own agendas before that of the people they serve, it won't really matter much who Americans elect.
In this country, elections sometimes seem farcical. In some counties, they actually are because puppet candidates are used or the elections are rigged and there is no way the contester can win. In India, I believe the elections have been legitimate, but that was not always necessarily the case.