When you say True 0% interest, does that mean after the promotional period is over, you can still purchase and pay back with 0% interest?
And deferred interest, is that basically charging you interest on all the purchases you made throughout the promotional period that they are now making you pay for?
So, what I call "true" 0%:
You get, let's say, 18 months of 0% APR. That means that you can charge whatever you want during that time, and as long as you make the minimum payments, you won't accrue any interest.
Once those 18 months are over, your APR goes to the normal rate (whatever that may be, depending on the card).
Scenario:
You buy $5,000 worth of stuff during the 18 months. By the time your promo APR expires, you have $800 balance left. If you don't pay that off by the statement date that your 0% APR expired on, you will have to pay interest on that $800, NOT on all the would-be-accrued interest during your promo period.
Deferred Interest Cards (store cards like Best Buy, Amazon (store card, not Visa), etc.)—
Scenario:
You get deferred interest for 18 months, during that time the company is keeping track of interest you would owe if you weren't on the promo. You buy $5,000 worth of stuff during that time. By the time your promo period is over, you have ANY balance left (even $1)...if you don't pay that off by the date your promo period expired, you will pay ALL interest that would have accrued during that entire promo period.
Is that kinda clearer?
Basically, promo 0% for credit cards are usually just that, your APR is 0% for that time, they don't keep track of any interest you would have paid.
Deferred Interest: Store cards. They are not scams (I have used the offers many times), but they can screw you with back-interest if you don't pay it off by the promo expiration date.
These will not be advertised as 0%, they will likely say "Pay no interest for xxx months" or, "defer interest payments for xx months"
Jazzy is right though, many might try to hide what actually happens, but just understand what they are and you can take advantage of them without worry.