Scratch tracks are pretty much a given for most recording sessions. Unless you get a whole band who wants to nail it in "real time.
I agree with everyone that the scratch should be tracked to some type of metonome - and better still to drum machine to allow for a little life in the groove. Rather than a flat stick click on the quarter notes, set up a rhythem, useing tambourine with a cabasa or some congas. This gives the players (in particular a drummer) something to groove to. And candidly, as someone who has played to click tracks for about 25 years, a sharp click track (sticks, wood block, etc) can be painful and can cause ear damage.
Also, I think it is very important to have a scratch vocal. If the players know where the melody line is going (and what the story line is about) it can influence the emotional content of their performances.