Re: so any recent applications for spouse visa?
Please do NOT even think about doing this! The reason why so many legit couples are facing extreme difficulties in their application process and why the system has become so frustratingly rigid and suspicious is because of such pathetically corrupt and immoral practices. And there has been a crackdown on this.
In regards to your actual question, yes you will either get caught or they will simply delay or reject your application if your payslips seems like they are from vague, small family or ghost businesses. It is not just earning a certain amount, the type of employment also plays a huge role. An application of an established accountant with years of history working in a top city financial firm is more likely to be favoured, then say an application of a retail worker with no proper job history or an administrator working in a small local business, even of he/she meets the earning requirement.
The system has become so strict and sceptical, and it is now beyond just the mere ticking of the tick list. A close attention to detail is being paid, and Home Office is using a lot of other judgements to assess applications.
But each application is different, and some people do get lucky and their application processed a lot faster, everything is possible. But I would strongly advise you against using any unlawful short cuts! They have very much stopped working.