This document summarizes key points to consider when selecting a microwave scattering or emission model for interpreting remote sensing data of geophysical surfaces. It notes that effective model parameters may not match actual surface properties, and that natural surfaces often have multiple roughness scales. Scattering is more sensitive to surface correlation than height statistics. Both surface and volume scattering can contribute, with volume scattering dominating at large incidence angles. Emission is affected by boundary porosity and dielectric properties. Ignoring surface features like loose dirt can lead to modeling errors. Proper model selection requires accurately representing the modeled surface characteristics.