The following advice is drawn from real founders I know who reported this bad VC behavior to me recently:
Even if it is to apologies that they will be slow to respond, just confirm receipt with the sender. Try to respond within 48 hours with a real response.
Remember: Your reputation as a VC is built from how you say ‘no’, not how you say ‘yes’.
You probably aren’t that smart anyway.
Not cool. Be clear on the next step.
And full disclosure: I’m guilty of some of this rude behavior above from time to time. I am trying to get better!