This will probably seem like common sense to a lot of people, but the number of times we are compared by clients on the basis of charisma scares me.
A lot of website developers are a little like the stereo typical Engineer or Accountant. We don't tend to have rockstar personalties. However some do and they can sell!
There is nothing wrong with this and I am jealious of this ablility. However the problem comes when they are selling themselves as something they are not.
Some typical examples I run into around the Gold Coast, Melborne and Sydney Website Developer market (its a worldwide industry issue) are 'Yes we are the premier Magento E-Commerce Developer we have made lots of stores' or 'We are top quality developers building highend/quality websites'. These are fair statements to make and Mr/Mrs Charisma is talking up a storm shows off the Portfolio and the client is impressed with all the shiny websites and very close to signing on.
Now here is the problem, not all websites Developers are the same. For example if you want to build a large traffic Magento E-Commerce store for your successful physical stores you need someone experience in doing this, a developer is not going to be able to just wing his way through it. So often we are seemingly competiting for business with another firm of 'similar skill' and we will look at the competitions portfolio and there is nothing relievant in their portfolio.
For example 5 months ago a client had decided to go with another company, which is fine. They said they just clicked better with them. The build is for a very large offshore Magento store website. I do my normal check out the competition and analysis were we could improve our services etc. I notice straight away there are not only no stores, but no Magento stores in their portfolio. Perplexed I ring the client and ask if they have seen the competitors website portfolio? yes they say its online. I say there are no stores in there were you aware of that. They were shocked, but rationalised that they had said they specialise in stores. I point out that saying you want to do it and having done it many times before are two different things. Especially, when it comes to large scale stores and Magento. I implored them to simple ask to see some e-commerce store examples and most importantly larger magento ones before they signed on.
The client was a little pissed at me, but I said hey I'm not saying go with us. I'm saying just do your do diligence and check who you are going with before you give them some money.
I don't hear anything for about four weeks. Then I get a call from the lost client and they say they have re-thought things and would like to go with us now. Well surprise! I ask why the change of mind? Seems that after much avoidance the other company could only offer up a small Wordpress store as an example of past work. When questioned hard the other development company said '...well really wordpress was a better option and they should really use Wordpress...'. The company still reassured them that they could do the job and they both agreed that they setup a quick mockup store in magento so the client could see what it was like. Well turns out they may have been to hard. Three+ weeks later and there is still nothing to look at.
If the company you are hiring doesn't have similarly complex examples of work then take a breath and put in some safe guards to protect yourself against failure or go somewhere else. The same thing can be said for design, however design is relatively cheap to demostrate, e.g. Make up one page or some samples in a similar style.
FYI. We setup a mockup magento site in a couple hours. Won the business and we continue to work together regularly to this day.