I am reading this paper in the link.
In introduction, paragraph 3, the last few lines are as follows
In theory, MC methods can be as ac- curate as MD methods, but MC may suffer from lower efﬁciency when using ﬁne-grained representation of the system, especially with large number of explicit solvent molecules. There is also a danger of biasing the sampling when using MC.
What does it mean danger of biasing the sampling when using MC. Is MC not reliable in protein/peptide structure prediction?