A nutrition tip from an iPhone app:
"Top a whole wheat muffin with all fruit jams."
This information might be useful, but at first I thought I was being instructed to put every kind of fruit jam onto a whole--not a partial--wheat muffin. Let's break it down:
"a whole wheat muffin" with no hyphen suggests "an entire wheat muffin," not a muffin made of whole wheat. Another sentence in this vein might be "I ate a whole apple." A hyphen clears everything up:
"a whole-wheat muffin"
Now for the second one:
"all fruit jams"
At first I thought it meant every kind of fruit jam. Another sentence in this vein is "All muscular men can flex." As earlier, a hyphen clears up the jam problem and informs us that it's an all-fruit jam.
So this tip is encouraging us to put jams that are all fruit on top of muffins made of whole wheat. We aren't supposed to pile on every jam known to (wo)man.
It's amazing how a lack of hyphens can confuse readers.