Why are odd-order intermodulation products, created within a receiver, of particular interest compared to other products?
Why Third-order products of two in-band signals f1 and f2 appear at 2f1-f2 and 2f2-f1, which land right next to the original signals. For example, 14.100 and 14.200 MHz produce products at 14.000 and 14.300 MHz, still inside the ham band. Even-order products (like f1+f2 or f1-f2) fall far away, near DC or near the second harmonic, where the preselector and IF filters remove them easily. That is why odd-order IMD, especially third-order, is the one that limits dynamic range and is the basis of the third-order intercept spec.
Watch out The claim about overloading IF filters confuses IMD with blocking or desensitization, and image rejection is a mixer and front-end selectivity issue, not an intermodulation order issue.
Odd order stays close: 2f1-f2 lands in band, so no filter can save you. Even order flies away and gets filtered out.