JFP I get what you're saying, and that makes perfect sense, but I looked at about a dozen sources and they all pumped the smoke into the intake. The several machine kits that I saw come with plugs and rubber funnels for the intake to accept the smoke hose. Here's an article from Popular Mechanics supporting the effort (not the DIY, but how to use it once I made it) that I pursued:
How to Find a Vacuum Leak - Smoking Out Vacuum Leaks
And here's a pro setup from Redline that goes for $1500 and the video showing how they connect it to the intake to fill the engine with smoke to find the leak.
https://vimeo.com/94463471