No.

No, not necessarily. In my opinion it is not primarily a question of
open or closed source, but more a question of whether code-reviews are
part of the development/maintenance process or not. Note that a
closed-source project may or may not have code-reviews. The same applies
to an open-source project.

Authors of open source programs do it for the kudos.  Their primary
motivation is to impress people by adding one "cool feature" after another.
Most can't be bothered to fix bugs -- adding yet more "cool features" is way
more fun.  The result is feature-laden programs that are buggy as hell.

Take OpenOffice, for example.  I won't use that program any more.  Each time
that I have used it, I have been rewarded by it simply vanishing without
trace, taking my document with it.

You'd hope so, but it doesn't seem to be the case.  However, there is some  
pretty poor code out there in some high-profile projects.

See http://www.jroller.com/page/fate/20060420 (contains strong language).

Dan.

I don't think there's any one answer to this, just as not every
programmer has exactly the same personality and motivations.

For me, this is not a motivator.  What makes me write good code is,
well, pride in workmanship.  Occasionally, I have written something ugly
in order to get the overall structure to a working state, but those tend
to be pretty well documented.  In the main, I want to have written
something to be proud of, whether it is going on my hard drive for me,
on the Alodar server for others here, to a client for a paid project, or
to an open source project for all to see.

Every line of code you write is a an expression of an idea, using time
you will never, ever get back.  It thus behooves you to write the best
stuff you can.  Since life is a series of trade offs, people optimize
for different things at different times - speed, space, prior knowledge,
what they want to learn next, but the wise are aware of that, and at
least try to select the optimization mix based on real needs, rather
than the voices in their head.

If I know something is going into an open source project, I may spend
more time making it maintainable, as many such projects have a wide
array of contributors.  I may also pick an implementation method that I
judge least likely to cause controversy, as time spent arguing about
trivia is time spent not fixing important things.

I may also have different amounts of time to spend, if I am working on
my own time, as opposed to working for a client.

If public acclaim and disdain motivate you strongly, then you may well
find that your open source work looks very different than your closed
source work.  Nothing wrong with that, as long as you are aware of the
motivation, and weigh it accordingly.

Scott