How does the "no late fee" work on Amex Clear & Citi Simplicity?

[Creditaddict]

One note to mention Amex doesn't seem to report a 30 day late until the account is actually 90 days late, does not mean I would be testing this!

Now this Clear Card it was good when it first came out because they were offering a 3.9% BT for LIFE... but as far as rewards go and paying late, you can get much better rewards and paying late on a credit card product with Amex a couple times is a great way to see a 10k limit come crashing down to $500 in a real hurry!

[shiftomnimega]

I inadvertantly tested this one December when I had a lot going on.  Never saw a missed payment on my credit report.

I remember them charging me with a fee, but then crediting my account back.