Hearing “Here, let me do that” on the sales floor always sets off alarms for me. I quickly want to know if this is a good thing or a bad thing.
If it is to relieve a customer of some irksome or tedious task such as filling out a long form or lifting a heavy object, then that is good customer service. But if it is to do for the customer something they can and would like to do for themselves, it is simply well-intentioned yet poor customer service. Here is a recent example.