Any observations can be submitted, but the observation has to be verified by a different observer. Most identifiers are folks with more experience identifying things locally, and the data quality is high. There's very little incentive to game the system and if something is misidentified other iNatters can also add identifications correcting mistakes which happens regularly - often various scientists/specialists tend to sweep observations in their taxa of note and correct issues. There's criteria for a "high quality" observation, including being verified. Only those observations that are high quality are used for training.