I'm glad you asked. When is voting bad for democracy? In all cases. However, you should still vote - it's a small expense - but expect nothing from the outcome. Voting is necessary, but not sufficient. Only direct action will yield the best results.
Voting is a waste of time and irrational, due to concentrated benefits and dispersed costs.
Voting only presents an illusion of choice. All political parties gravitate towards the center due to Hotelier's theorem or the median voter theorem.
Voting doesn't actually represent the people, and only elite special interests get legislation they want passed.
The only real democracyreal democracy is one where every day decisions are made constantly on an individual basis, and it requires allowing you to withdraw your consent.
Voting only presents the illusion of freedomillusion of freedom. You are subject to the whims of the majority of people, and never really free. You have a better chance of winning the lottery than influencing an election.
Voting is rife with corruption, due to the principal agent problem.
Voting is essentially: