It doesn't really matter as long as your startup is good, people really could care less. Besides with an open source startup people can help you debug. Which is exactly what the people I am working with did. https://github.com/lefnire/habitrpg https://github.com/lefnire/habitrpg/wiki/Business-Model
We even got a kickstarter for our open source startup http://www.kickstarter.com/projects/lefnire/habitrpg-mobile
So no it is not a bad idea to open source your startup just be careful.