Hahaha! Of course, 'entertaining clients'...
Erm, your last paragraph? Would love more knowledge about that!
I think they've closed the loophole now (if not, it's next year), but as the dividend tax rate was so much lower than the income tax rate it meant you could save a lot in tax. Example for 2015/16:
You make £80K profit in a year as a sole trader (for the meantime, we'll ignore having a Ltd company and paying yourself a director's salary as that's the very worst option).
You would have a personal allowance of £10.6K
You'd pay NI of £4K
Income tax would be £21.4K
Your take home would be £54.6K (Taxation of £25.4K)
If you took the entire £80K as a dividend:
£80K profit
£10.6K salary (as it's tax free and paying the NI keeps you eligible for a state pension)
Total NI of £650
Gross profit for the company of around £69K
You'd pay corporation tax of £13.8K leaving a company profit of £55.2K
You pay it all as a dividend so your dividend tax is £6.7K
Your total take home is a little over £58K with a total taxation of just under £22K
It gets a little more complicated over £100K as they take your personal allowance away between there and £110K. It becomes really beneficial in the top tax bracket.