Is Engine filter replacement necessary even when it looks good?

I've driven in Alaska, hence the

The bad thing about sucking a mime into your airfilter is that you can't hear them so unless you notice the drop in power you cant tell they are here. OTOH, removing a mime from public areas is a service to mankind, so thank you for that.

 

They have a place, just not a voice.

 

I agree with that, but perhaps we wouldn't agree on the place.

 

Just a side note:

I bought a used car that had a K&N air filter.
First time I removed it and held it up to the sunlight, I saw all these pin holes of sunlight shining through.
What are those?

I threw it in the trash and bought a standard paper filter.

 

There really is no need for a K&N filter.

 

Evidently, some "doodus" tried to clean it with a compressed air gun.

 

KN with let more dirt in your engine, not worth it. plus no real advantages.