Not True.
See they broadly have 2 brands - John Jacobs and Vincent Chase. Both are owned by them. I'm not talking about fossil and other 3rd party brands.
Now, If you talk about John Jacobs, It does have better designs and is way costlier. But sometimes john jacobs also comes in sale.
Talking about Vincent Chase, it doesn't matter whether you buy from 60% section or BOGO, The quality is exact same. I've purchase more than 8 items from them.
And, saying that sale items are lower quality is absolutely wrong.
I visit their store often to try before i buy. Many of the frames available at MRP in-store are at 60% discount online.
Also, Lenskart's quality is far better than local stores.. both lens and frame with not a huge price gap.
Bluecut are costlier at lenskart.. but antiglare and progressive cost less than what you'd get offline.