Due to the inherent combination of image, video, audio and 3D-models in new MPEG standards like MPEG-4, robust 3D-watermarking is becoming more and more popular to ensure data authenticity and integrity. Beside the design of 3D-watermarking schemes, the evaluation is necessary. In the paper we analyze currently proposed 3D watermarking algorithms for weaknesses that may possibly be exploited in watermarking attacks and derive according design principles for improving algorithms. The paper makes contributions in three respects: First we analyze properties with respect to preservation of surface continuity and symmetries. Second, we analyze how algorithms proposed by Ohbuchi et al. and Praun et al. compensate for errors introduced through imperfect mesh resampling. For Ohbuchi et al. algorithm, we explain how spectral decomposition can be applied in directions other than canonical coordinate system axes in order to minimize errors introduced to resampling. With an experimental prototyped algorithm based on spectral decomposition, we demonstrate a significant increase of robustness of features with respect to errors introduced in resampling. Third, we analyzed the general effects caused by polygon simplification on watermarking algorithms, which, from the results from Praun et al. can be considered as a “critical” operation. As a first result of our analysis, we present a modification of Praun et al. watermarking scheme detector trying to improve compensation for these effects.