I like the thought, but I'm going with the puke making the smell on it's own as normal human vomit. It's also possible (though not probable) that some zombies hit the furniture store between Lizzy leaving and Burt and Saul arriving.
I've sadly cleaned up enough vomit in my day to know that delightful combination of stomach contents and bile can stink up an area pretty easily. Saul and Burt were following the trail to the bed where she puked, but remember she also puked somewhere between the bed and the front windowbwhich could make it easier to smell.
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