Rising concerns over actual benefits of carbon credits

There are rising concerns over the actual environmental benefits of some of the carbon credits being traded.
Most prominent concerns are :
1. HFC scrubbers (critics are complaining that these should have happened anyway, and should not be used to earn millions in carbon credits as they involve very little effort)
2. Some voluntary market schemes, like tree planting, which are not verifiable and not evaluated in details.

Also read : Concern as carbon traders scoop billions