Can i tell a stranger that her boyfriend is too ugly and annoying for her?

I was shopping today and noticed a young couple around in the store. I was minding my business, but somehow they kept ending up in the same area as me. They were loudly talking and just existing a but obnoxiously, or should i say he was. 

I couldn’t help but listen. He was so annoying. I hated hearing his voice and looking at him, so i tried not to. I got in line to check out and guess who got in line behind me. The couple. 

I kept hearing him say things along the lines of “stop im not acting weird” and even (the kicker) “i’ll bike you home but im not going inside. I dont want to hang out anymore i have to play overwatch” (he must like Sinatra). 

Anyway, she asked him to put one of the shirts she was going to buy back on the rack, and when he walked away to do so i turned arounf and looked at her. I complimented her bag and her shirt. They were very cool and she was very cute and kind looking. Unlike her boyfriend. Anyway i thought that i was going to tell her “you seem very cool and sweet. I dont think your boyfriend appreciates that and he isn’t good enough for you” i mean, he was wearing a drawstring backpack and a silver chain with one of those ugly tropical themed shirts from pacsun or

Something. 

Should i have told her that her boyfriend is gross and ugly?