The long-range surface structure of the dichalcogenide MoS2 is probed with nanometer-length spatial resolution using low-energy electron microscopy (LEEM) and microprobe low-energy electron diffraction (μ-LEED). The quality of two differently prepared types of MoS2, single-layer and multilayer exfoliated crystals, as well as single-layer chemical-vapor-deposition (CVD)-grown crystals, is examined. The effects induced by a supporting interface are examined by utilizing two different substrates, SiO2 and native-oxide-covered Si. In addition, the role of impurities is also studied by way of in situ deposition of the alkali-metal potassium. Microprobe measurements reveal that, unlike exfoliated MoS2, CVD-grown MoS2 may, in some instances, exhibit large-scale grain-boundary alterations due to the presence of surface strain during growth. However, real-space probing by LEEM in conjunction with k-space probing by μ-LEED shows that the quality of CVD-grown MoS2 can be comparable to that of exfoliated MoS2.