Sure you can.
Libel is only actionable if the target cares enough to MAKE it actionable.
What on earth would McDonald's have to gain from me?
That is EXACTLY why so many people are able to pull off BS in the pinks, and quite honestly sometimes on the big board.
You may be lying, but it might not be worth my effort, time, or money to do anything about it.
Now if you are somehow HURTING me, then I am more likely to do something about it.
In a case like this, it wouldn't be hurting McDonald's for me to say that. It doesn't excuse it, or make it OK by any means. It is sneaky, and crappy, but that would be the point if I was trying to FOOL you.