Enough of DC

AD
BC

Two letters sometimes denotes an era

This ad of DC made me think that finally DC has shifted from sensuality to sensibility. “Wow” was my first expression toward the hoarding on my first sight of it near Tidel Park, “nice piece of creativity from the ad agency” was what I told to myself, I thought it definitely would be a hit, but the excitement existed only till my second look on it turning around from my bike, and now I added an S before the hit. Now, go to the top and read the caption again, it should have been “denote” not “denotes”. This mistake seems to be silly but it is not so. To me, it raises the following questions:
1. Is an error in subject–verb agreement acceptable for a newspaper?
2. Was it the mistake of the copywriter or the publisher or was it a typo?
3. Has anyone proofread the content?
4. How come a grammatical error happens in a one-liner.

DC needs to be Definitely Careful.