You're walking down the street and see a sign in a new sandwich place saying they have a three-for-one deal on, buy any one sandwich and get two sandwiches completely free. Sounds like a great deal, it might be a bit much but you skipped breakfast today and you can always keep one for later anyway, right? So you head inside and think about what you want, maybe you're cutting back on red meat and you're tired of chicken so you go with a tuna or cheese sandwich. You get to the counter to pick up your tuna+cheese sandwich, the worker hands over your two freebies and you walk out. Turns out you're hungrier than you thought so you practically inhale your tuna+cheese, barely savouring the flavour. You reach for your second sandwich but when you unwrap it you discover it's not the same as the one you ordered; it's bread with a thin smear of butter, technically it is a sandwich but it's definitely not what you wanted or expected when you ordered.
Did you get scammed? Are you okay with that since you still got one sandwich even though you chose that vendor because they advertised three?
It really shouldn't be a controversial statement to say that lying to people to get their money is wrong. If it really makes no difference as you're suggesting why can't they just advertise the real value instead?