If you have applied for a job recently, you just might find yourself regretting that ill-advised late-night Tweet, or that dodgy photo on Facebook.

A survey commissioned by Microsoft to coincide with EU Data Protection Day has revealed that 43% of European recruitment professionals routinely analyse prospective candidates’ online reputations before deciding whether to select them for interview.

Content drawn from search engines, personal blogs, and social networking sites all falls into the scope of the pre-screening techniques being applied by many HR professionals across the EU.

The report, conducted by Cross-Tab, indicates that across Europe 23% of recruiters have gone as far as rejecting candidates based on their online reputation, whereas this rises to 41% in the UK, the average being driven down by rejection rates of only 16% in Germany and 14% in France.

Germany, however, incorporates online data into its candidate assessments in 59% of cases, with lower figures recorded elsewhere across the continent.

If this sounds grim for European job hopefuls, think about those applying for new roles in the USA. There, an amazing 70% of HR professionals admit to rejecting clients based solely on their web-presence.

EurActiv reports that the most common reasons for candidates being rejected in this way is through the discovery of “inappropriate comments or text written” by the applicant or “unsuitable photos or videos”.

So be aware, the survey suggests that in Britain only 9% of people consider their online reputation to be a significant factor when applying for jobs.

Draw your own personal line in the sand and try to stick to it. Once you’ve said something, it’s out there pretty much forever. Maybe that age-old saying, a favourite of Mums all over the world, might be more relevant than ever in the real-time, always-on, social web… “If you’ve got nothing nice to say, don’t say anything at all”.

The EU Commissioner responsible for Data Protection, Viviane Reding has vowed to increase citizens’ awareness of spreading their personal data across the web.