I See that, to a die-hard fan, tribute bands could be offensive.
It's strange, however, there is a thin line between being cool or being offensive.
If a pub-band plays a very well played DS set during the concert, It's fine. This little band is paying their respect do DS.
However, when this little band realises there are enought audience interested on more DS songs and they turned themselves into a serious DS cover band.... Oh, no. This is outrageous.
And if this little band starts touring as DS Cover Band... Ufff. It's a deadly sin.
If you don't like DSL, don't watch them.
The same as for any cover band that you dislike.