@ancagavs is right. Many deals dont have expiration dates. But you're right, if it specifically says "promotion ends _____" or something like that, then you should take the 10 seconds to add the expiration date.
Especially around Black Friday and Cyber Monday, many of them had true expiration dates listed, but no one was posting them.
bbattag (rep: 6.8k) posted Dec 03, 2012
4 days ago
Feb 20, 2016
Mar 18, 2016
Mar 27, 2016
15 days ago
23 days ago