You can record a local audio file with Skype now. Isn't that cool? https://support.skype.com/en/faq/FA12395/how-do-i-record-my-skype-calls
Interview shows are one of the most popular styles of podcasting. If you podcast long enough, you're probably going to end up talking with someone over Skype, and you're going to talk with guests who don't have good microphones and don't understand how important audio quality is, or what they can do to prevent common issues like background noise or room echo. It's your responsibility to clearly explain what you need from your guest. If you leave it up to chance, don't be surprised if they send you a recording with poor audio quality.
I'm fed up with listening to podcasts where the guests sound like crap, so I decided to do an episode about how to get a better audio recordings from your guests (or even your co-hosts).