"patents they've never disclosed" is kind of a contradiction in terms. Usually the claim is that they haven't disclosed which patents are being cross-licensed.
"Patents they've never disclosed" is acurate. They go to companies using Android and say - "Linux uses our patents, pay us or else.", but they never disclose which patents Linux infringes on - they just take the money for a no-sue promise.
Other things that will set off the detector/test if you handle your lugage at any time while contaminated with them include:
- potting soil, grass patch, plant food, and of course straight fertilizer.
- Cleaning products - anything with amonia in it.
- attending a show with pyrotechnics
- gun powder residue - black or smokeless.
- nitrate based medicines for heart conditions
The list goes on, but the point is, even transporting your lugage in the same trunk as you carried potting soil in 2 months ago is going to get you flagged as a positive. After that, it's going down hill for you.
Even when the idea is worth the patent, by the time the lawyers get through with it, it's entirely worthless to actually try and duplicate it. General and vague references that paint a broad picture of the problem supposedly solved and hints of how to do it.