We have decoupled the intrinsic electrostatic effects arising in monolayer and few-layer MoS₂ from those influenced by the flake-substrate interaction. Using ultrasonic force microscopy nanomechanical mapping, we identify the change from supported to suspended flake regions on a trenched substrate. These regions are correlated with the surface potential as measured by scanning Kelvin probe microscopy. Relative to the supported region, we observe an increase in surface potential contrast due to suppressed charge transfer for the suspended monolayer. Using Raman spectroscopy we observe a red shift of the E¹_2g mode for monolayer MoS₂ deposited on Si, consistent with a more strained MoS₂ on the Si substrate compared to the Au substrate.