No
Experts’ time is valuable. Courts would not be able to get qualified experts to testify if they were not compensated. As per your previous question, the crucial point is that they are paid to tell the truth, not to be an advocate for one side.
But Sometimes Yes
There have been scandals where a cottage industry of experts sprung up, based solely on there being a market for expert witnesses. These witnesses knew that the way to keep getting hired was to always confidently testify that they could prove the defendant’s guilt beyond a reasonable doubt.
Bite-mark analysis is an entire field which is now held to have operated as a pseudoscience, and where some prolific “expert witnesses” were caught committing fraud.
Similarly, the Texas Forensic Science Commission conducted a review of numerous wrongful convictions for arson in 2012, although there the motive was not money. They were not being paid to testify one way and not the other. Forensic examiners in Texas were simply basing their testimony on myths and old wives’ tales handed down by their predecessors, which turned out to be false when tested under the scientific method. When put to the test, accidental fires could cause all the signs that Texas forensic examiners had sworn were proof of the use of an accelerant to commit arson. Again, though, these “experts” got their jobs by always giving the prosecution the evidence of guilt it wanted.
I have listed examples of experts shilling for the prosecution, mainly because most of the cases that come to mind of highly-compensated experts shilling in defense of someone work for corporations on what are more political than legal controversies.
HoweverEven Then, not Really
Even in those examples of misconduct (or incompetence), the false experts were caught because the defense was allowed to hire experts of their own. If the only experts allowed to testify had been the state’s forensic examiners, no one would ever have tested their claims about the difference between arson and accidental fires scientifically. Even though they had no direct financial incentive to testify, they saw their jobs working for the state as working for the prosecution.
Removing the financial motive would not remove all possible bias or suspicion of bias, either. For example, in the wrongful-conviction reviews of both bite marks and arson, one of the most common counterarguments were that the experts arguing to overturn the convictions of people who had no money to pay them were passionate opponents of the death penalty, and therefore supposedly biased.