How to Make Low Perception Rolls Interesting When Your Party Travels

What's the classic problem of a DnD party travelling and taking watch?

DM: Roll perception check please.

Rogue: rolls...uh, that's a 4.

DM: -nothing interesting out here-

The players essentially gain no advantages or disadvantages from that. It's not interesting and they start to wonder if there's any real issues or dangers for them to face in the wilds. And that my friends is where you get the perfect opportunity for a misfire from the players.

In our session yesterday, the rogue and the bard were on watch outside the players camp (Galder's Tower), the bard on guard while the rogue did a patrol. The perception check was poor, below 5, and something needed to happen.

This was the description I went with:
Rogue, you round the first corner of the tower, taking your time to make sure nothing is sneaking up on your camp. The second corner, it all looks well. The third corner you hear some faint movement around the next corner, and as you go to peak, you see a tall humanoid figure in the darkness, peering into the door of your tower. You raise your crossbow, readying up for a problem and you realise it's the bard.

True, nothing of major import happened, no wild beast charged them down, but it gave the players a moment of light heartedness but also a reality that low perception checks may start to cause problems for them. It's nothing fancy, but at least it wasn't the same description for a low roll as a high roll.

What do you guys think, what do you do for perception checks on travelling and camping?

Once more, yours from inside the sack of a dice-obsessed goblin,
tomster-17