Is it wise that employers compare your expected salary with your current salary?

Salaries must be linked with the efficiency and commitment of the employee,which can be noticed from the employer a long the year.the strong guys must be rewarded and the beginners and weak guys must trained enough to get well.expectations always different and variable from both employee and employer.The FACT is that the employee will never get what he expect and the employer always have a ceiling that can not be exceed. 

In my opinion, no. There are chances that someone who is really capable of achieving more could have been placed in a wrong position for some time. and given chance in a suitable position would actually improve the outcome. I know some one who was appointed in an organization for few years with a pay of $1400. and the same person after given a chance with little training was hired for $12000. Comparing the current salary is only a method of negotiation in my view.