In Hostile Opposing Counsel Expert Communications.com writes:
I have been doing expert witness work for 25 years. Attorneys basically have two tactics. They can either attack your opinions or attack you personally. If the whole deposition is about attacking you personally, you know you have won! If you the attorney could attack your objective opinions, he would certainly do so. If he refrains from attacking your objective opinions, he knows you are completely accurate. Therefore, since he can’t directly dispute your opinions, he can only attempt to discredit you and therefore, by implication, your opinions.