You attain much more respect by admitting your mistakes than by ignorantly casting them aside.
We've all known or worked with someone who "defends bad ideas". If you have defended a bad idea, made an error or simply fucked up... don't be afraid to stand up and admit it.
No, you wont get shot. And you probably won't get fired either. It happens. We all goof every now and then.
And while I am on a rant... we all have opinions. Some have valid reasoning, some not. If you are one to claim things like "the usability of this ___ sucks" or "this is poor use of _____" or "anti-aliasing looks better" or... just be prepared to justify it, and back up your statements.
You see what I'm getting at? Don't take things personally, try avoid biased opinion and think objectively please.
Now back to your regular scheduled programming.