Cost of Ready Made Companies
A potential drawback of purchasing a ready made company is that it is generally more expensive that the cost of setting up a new one.
For a typical off-the-shelf company there is the cost of the registration itself, probably a name change and the fees (in some case) to verify that it has not traded. If the company has conducted business at some time in its past, then there is the necessary expense to commission adequate due diligence work.
Creating a False Impression
Having a company which has been in existence for a number of years is generally judged to be a benefit of ready made companies. That might, in some cases actually have an adverse and undesirable effect which the new owners might not have previously considered.
The perception that the ready made company is stable because it has a reasonably long life is only valid if a particular third party (usually a customer or supplier) also has that particular view.
It is possible for a negative outcome to occur if the person has the view that the whole purchase of the ready made company was undertaken to create a false impression. Suspicion and mistrust may dominate that person's perception and thus having a ready made company has in fact had a detrimental affect on the company's ability to its conduct business.