If all of the rules and boundaries are followed and everyone is happy, there really isn't any harm in living together this way! What happens at the swing party stays at the swing party. It doesn't have to be a new car or anything, just something that lets them know you care, and that you'd like to keep being invited to their sex parties. A lot of clubs not only provide condoms in-house, but also expect you to only use theirs. A no thank you sounds a lot nicer than a no way! All clubs and all parties are going to be a bit different.
A Swinging Relationship Can Be Healthy For You, if You "Follow the Rules"
Be polite and show common courtesy. Bring Your Own Condoms. You might just find you like it a lot more than you thought you would. If all of the rules and boundaries are followed and everyone is happy, there really isn't any harm in living together this way! Be neat and tidy.