There are pros and cons to outsourcing your SEO and link building work.
Pros:
1. Lower costs for your company - Not having to source, hire, train, and pay for an in-house SEO team can save you a lot of money.
2. Lots of choices - If you have a business process that you'd like to outsource, there's probably several companies out there who can do it for you.
3. Experience - Outsourcing link building to a company saves you the time from learning the ropes by yourself. They take the guesswork out of the equation and just give you the solution you need.
Cons:
1. Lack of control - Because these people are usually not in your direct area of influence, outsourcing can be prone to error.
2. Lots of choices - Yes, this is also a con. Because there are too many players on the field, it may be difficult to tell apart the experts from the 'horror stories.'
3. Language barriers - Communication with someone from another country can suffer because of the language barrier. Your instructions may be clear to you, but can be misinterpreted by a non-native English speaker.
What can you do to make sure that you're outsourcing SEO right?
1. Be clear about what you want, when you want it, and how you want it - Sure, it may take a bit more of your time to create a process, but it will be worth the time and headaches you save by reducing the errors your vendors may commit.
2. Do your research - Oftentimes, clients outsource their SEO to someone who promises "Instant Page 1 on Google." If you did your research, you know that this is probably untrue (unless they're Google or Charlie Sheen). Know what they're offering and what you're paying for - it's all about managing expectations.
3. See if they practice what they preach - Do a link:sitename.com query on Google to see if the company you're outsourcing to is doing their own SEO right. If you find that they use blackhat techniques to inflate their own rankings, you might want to stay away from them with a 600-foot pole.
It's true, outsourcing can sometimes be a nightmare. But with a little preparation and research, you can make it go smoother.
Cheers!