I think abusing RFID tags is extremely against the spirit of the game.
As Xenon pointed out, you can cut through the RFID chaff by simply searching for specific icons rather than generating a list of all icons.
It's more effort for a GM because he's got to play a smarter hacker if he's going to really mess with you. But ultimately, if your team's hacker isn't doing his or her job and watching out for Matrix threats you're still going to get hacked to hell and gone.
Matrix Perception "What is the Agent doing?" and a continuous edit file action and the Hacker can go about his normal sabotage.
Not all NPCs are going to be able to employ this method. Corporate gear is going to be tied to a WAN and the number of marks isn't going to be static. Every time someone logs in or out, or accesses a piece of corporate gear the number of marks is going to change. But, IMO, Corps should be using Agents for monitoring duty. Any facility is likely to have Agents assigned to it. If those agents aren't busy they should be tasked to security. Heck, security should have some exclusive agents monitoring key vulnerabilities or assets, IMO.
Smaller groups should be using Agents too, since they likely can't afford a high rating host and a full time team of security spiders.
Agents! For when you just can't afford the good stuff!
And, thank you. My Samurai's like cybereyes. And want to keep them. And FWIW my own hackers use Heavy Pistols or SMGs to brick cybereyes.
I find it interesting that Samurais usually have more vulnerabilities than a decker and a fraction of the ability to defend themselves. Its a nice challenge when the standard powergamer response of "throw more dice" isn't a viable option.