Keep in mind that advertising more specific prefixes is also how route hijacking works. 
That's why it's important to only accept the range that the original resource holder specifies. 

If the owner knows that their prefix will be advertised as a /22, you permitting the containing /24s allows someone else to advertise them and attract the traffic.

Think what would happen on the exchange if someone took one of your prefixes and advertised more specifics?

On Monday, January 6, 2014, Dean Pemberton wrote:
Most of the invalid ones are on there because people are advertising prefixes more specific than their ROA covers. 

Ie a 22-24 Roa and then advertising /28s on the exchange. Or more likely a 22-22 Roa and 24s on the exchange. 

It's as much about getting the range right as it is about the originating as and prefix

On Monday, January 6, 2014, Michael Fincham wrote:
On Mon, 6 Jan 2014 11:26:24 +1300, Dean Pemberton wrote:
> Anything that turns up as an "I" on this list, I'm going to be looking
> at pretty carefully before I prefer into the CARDIGAN network.

Cool. I think I see some of our prefixes in there, which is probably a
mistake :)

I'm travelling today but I'll be having a close look at this tomorrow
myself as well.

Michael Fincham
System Administrator, Unleash
Office: 0800 750 250