As per Tanaquil’s response, I tend to agree. I have only had exposure to advisors from the seller (my company being the buyer) and their interests were greatly linked to how big a fee they would receive. They are there to provide a service and get paid, not for the future potential of the combined entity.
This can help both ways though. The seller’s advisors can be used to help close the deal from a Buyer’s perspective as they can convey messages whilst being considered more trustworthy in the eye of the seller.