Speaking parts ruin television

You’re watch­ing your hour-long drama/mystery/police pro­ce­dur­al show on tele­vi­sion, and your heroes engage in con­ver­sa­tion with a hith­er­to unknown guy or gal on the street, who just hap­pens to be hang­ing around. Giv­en that speak­ing parts pay much more than stand-around-and-nod-silent­ly parts, you can bet your sweet plot­line that the guy or gal had some­thing to do with the drama/mystery/dead guy. It’s a dead give­away, but what are you going to do? Spend more to have a lot of red her­rings jab­ber­ing away? I don’t know. Do you have any sug­ges­tions?