Not saying 0.0.0.0 should be used in this case, but if you have data sniffing software listening on port 80 or 443 without your knowledge (or really any port at

Not saying 0.0.0.0 should be used in this case, but if you have data sniffing software listening on port 80 or 443 without your knowledge (or really any port at all, but especially a privileged port), you probably have much bigger things to worry about than some ad hoc PoC sending data there.