What are the pros and cons of hiring contractors and consultants from the employer's perspective? If you are a manager, product owner, senior engineer, or someone higher up with the company's better interest at hand - are there any downfalls to hiring from consulting/staffing/recruiting agencies, whether just as contractor, or as contract-2-hire?
The following question answered the pros and cons of being a contractor (such as taxes, benefits, treatment at work, ect).
More specifically, is there an affect that hiring contractors has on the product, company culture, or productivity level of team members? Are contractors more wild cards in terms of caliber, or are they not worth what they cost?
There may be a difference between hiring contractors in general, versus hiring from specifically staffing firms - so if you think I should break up this question, I will heed that suggestion. I ask it this way because I am interested in larger trends.