You may be recording your demo for a number of reasons. You may be an independent musician recording music to send to major record labels for a record deal for yourself or band, or you may be a songwriter for genres you don’t perform. Specifically in reference to writing for genres you don’t perform, you want to make sure that your vocals are clear and audible as possible. If you’re writing a song for Lady Gaga, and your demo recording is not audible, then you do not have a chance of getting that song to her. In the rich market of the music entertainment, songs are going to pass by the ears of music supervisors, project managers, and artist managers, before they are actually heard by the band or singer you wrote the song for. So, as you anticipate success, you want to make sure when your intended target (the singer or band) gets to hear your song, they know what you are saying.
Recording songs that you know very well (because you wrote them), can give you more time to develop harmonies. If you are recording a song for someone else to sing, then you want to make sure the lyrics, or songs strong points are clearly heard. Sometimes, songs strong points are the songs harmonies. Also, if you’re recording a demo for other artist to sing, you don’t want too much effects on your vocals because you want the listener to be able to focus on the lyrics. Of course if you willing to pay a thousand or two, then you can have you demo recorded by a professional singer, productions team, and a master engineer. When writing songs for other artists, the most important thing is to be able to make sure they can hear the vocals, not necessarily bedazzle them with sound effects. Some music supervisors you submit your music to are looking for specific music to edify themes or trends; some record labels are looking for lyrical rappers, and if people can’t hear your voice because you put a body shot of reverb on your lead vocals, then the chances are, the supervisors are going to pass on your music.
So you need to make your lyrics audible, especially if you are submitting your music to be sang by major music label artists. If record labels like your tracks, then they’ll re-record with their artist singing them. Yet, if they can’t hear your lyrics or words, then the chance are, the label will not be choosing your song because in the business of music entertainment, songs are pitched a dime a dozen.