If you put a good faith deposit on a condo and find that there is a lien on it can you back out?

Your realtor can answer your question.

There is usually a period between the payment of the good faith deposit and closing, during which you investigate matters involving the purchase of this property.

In turning up a lien, you've done your job.

Whether you can obtain a refund of your deposit or not, depending on whether or not the lien was disclosed or required to be disclosed, is a matter that your realtor can advise you about.

If you want to 'back out' of your offer, this may not be the best valid reason to do so, given that in the course of transferring title, the lien must be satisfied in order for clear title to pass to you. This process is pretty automatic.