Sponsored tweets will only find their way into Twitter searches if, according to Twitter's COO Dick Costolo, they 'resonate with users and are part of their conversations'.
Christian Mahne, head of Lansons Live, told PRWeek the development had 'elegantly raised an impossible bar for commercial twitterers'.
Mahne added that meeting Costolo's test would be difficult: 'Have you ever tried to write an email or tweet that can simultaneously appeal to everybody? This just is not a skill that anyone has, let alone big brands, so all you end up creating is spam.'
However, Waggener Edstrom senior digital consultant Jon Silk pointed out that the 'subtle' nature meant they would not affect the user experience too dramatically.
He added that the service could prove invaluable for an organisation dealing with a crisis: 'The brand or organisation involved could place a tweet at the top of the stream and connect immediately with everyone searching.'
Twitter launched Promoted Tweets as its first major initiative to start making money out of an estimated user base of 105 million. The move comes as PRWeek reveals how journalists would prefer to be pitched via Twitter.
Paratus Communications senior consultant Adam Vincenzini and K/F Communications' programme manager Lacey Haines researched attitudes among senior journalists in the UK and US. They found the continued 'novelty' of Twitter pitches makes them stand out. One respondent from the News of the World said that, in contrast to hundreds of daily emails, only one or two pitches arrived via Twitter.