Seen things done every which way over the years, with differing results.
Had plod catch us bang to rights, sat under a hedge squeeking. Told em to shush and get down, as a fox was coming in, so they did (!!!), and hung around to see the run, which (thankfully) was a miss, but they were fascinated.
And though I've always gone down the 'diplomatic' route, I've got mates who've torn into them with vengeance, and gotten away with it.
As McH says, never admit to anything, find any alternative to your real activity, give them nothing.
Worked for me for my first three trips to Orm