Years ago, I bought a table at a vintage mall. I looked the table over from an upright position, but didn't crawl around on the floor or look up under it. It wasn't until I got home that I saw there were major hidden structural issues and the leaf that came with it didn't work at all. What a lesson.
The tag did not say "as is". There were no notes about the issues.
You could argue that I was buying a vintage table and should expect wear and tear. I should have looked better. I should have insisted on seeing the table set up with the leaf in place. I should have crawled up under the table and examined everything. Seriously? How many customers would do all of that?
I my humble opinion, the vendor did a very bad thing for herself AND for the store. She destroyed trust.
In our business (as in used car sales) an omission is basically a lie. When a customer feels they've been lied to, they likely won't buy from that vendor again. Worse, they may feel the whole store is dishonest and may not come back to the store at all. I'm always shocked at how many customers don't realize that an antique mall is made of of lots of booths run by different people. They don't consider that some vendors are more reliable than others. When they form opinions, they lump the entire store together.
Honesty is the best policy!
If you take the time to point out flaws that may not be noticed 'til a purchase is made AND mark your price accordingly, the customer can decide if it's a flaw they can live with and they may still make the purchase. Furthermore, having the flaw noted builds trust.
Update: One of the commenters to this post had a very good point. Sometimes things get broken in a booth and the guilty customer just sneaks the item back on the shelf and doesn't tell a soul. It can sit on a shelf like that for ages before the vendor sees that it's damaged. But if you KNOW about a flaw, you'll be better off in the long run to be up front about it.