Subject The article reviews misstatements arising from appraisal when three key valuation methods are used, i.e. income, comparative and cost methods. I also focus on valuation practices and instances when the above methods are inconsistent with the theory and adequate information resources. Objectives I identify key errors and show instances of abuse as part of key valuation methods, and propose methods to assess such instances and prevent misstatements. Methods The research is based on methods of analysis, synthesis, and formalization in identifying and describing valuation errors. Results I refer to multiple cases and examples to illustrate the incorrect use of valuation approaches. The article also describes key theoretical provisions of valuation, which should be applied to detect errors and abuses of appraisers and cost analysts. I suggest what mechanisms should be used to prevent valuation abuses and show how modern information systems can work to correct inadequate valuation results. Conclusions and Relevance In the time of market turbulence, unbalanced information and key indicators, appraisers tend to commit a lot of incidental errors in reports and abuses by deliberately misstating valuation outcomes through manipulations. Referring to such instances identified and described, methods to detect them and proposed measures to adjust valuation procedures for available information, appraisers, cost analysts, users of valuation reports will have precise value benchmarks, compile unbiased economic indicators in order to make adequate managerial decisions.