Someone had slightly spoiled the effect by putting a kettle on one end.

I did not look back, for fear of spoiling the effect.

To my way of thinking, it spoils the whole effect.

Finding out that I apparently couldn't even remember their names in the right order rather spoilt the effect.

Closer up, though, the frown spoiled the effect a little.

The only thing that spoiled the effect was her glasses.

Then he took a bite of pizza and spoiled the effect.

But then she had to spoil the effect by adding, "I did it for a very good reason, though."

It stuck once or twice, which rather spoiled the effect.

She spoils the effect by not being able to hide a small smile.