"I know they're not a 'big fan' of my blogs. That article they tell me they enjoyed? They probably never even read it." I'm speaking with friend, and blogger, Gemma Cartwright. Cartwright has been blogging both personally and professionally since 2002. She's currently the editor at Popsugar UK, but she's completely fed up with poor approaches from SEO agencies. "It's formulaic and dishonest. Don't fool yourselves – we recognise a template email. Lay out from day one what you're looking for. And know that I'm under no obligation to help you."

Search Engine Marketing is fundamental to digital marketing. I often adapt the old Bill Gates on PR quote saying: 'If I only had two dollars left I would spend one dollar on SEO. And probably the other on pay-perclick (PPC).' But I'm hearing a lot of stories – from brands and agencies – suffering the consequences of poor-quality SEO.

Gareth Morgan, MD of UK-based Liberty Marketing, told me: "Many of the smaller agencies outsource or automate the work they do, so they can charge a lot less." This gains short-term results now, but risks an expensive rankings penalty further down the line. And a quick rankings boost is not what modern SEO is all about.

Effective SEO now involves web design, usability, coding, social media, PR, and content marketing. Daily activity varies between keyword research and analysing reports, to content creation and blogger outreach. Morgan thinks that "a lot of agencies and in-house teams are struggling because they don't have all the people and skills in place".

If agencies continue to offer cutprice services – and brands continue to hire them – the whole activity could be a waste of time. Cartwright confirms dodgy tactics abound. "Often they mislead bloggers by coercing them to include specific links in a post that hasn't been agreed up front." Less experienced bloggers are often told that they're dealing with a PR agency. They want to build a media relationship with the brand. But aren't aware they're doing something that could hurt their own, and the brand's, website.

Brands need to get up to speed with the latest in good, and bad, practice so they can spot a bad search agency before they hire them. Cartwright cites PR as a great example of industry turnaround when it comes to digital strategy. "I've seen a real change in the quality of most PR outreach in the last year or so. They now recognise the power of bloggers and strive to treat them like professionals."

So what are the signs that an SEO agency could be a wrong 'un?

Outrageous promises. As Benjamin Franklin said, the only thing certain in life is death and taxes. There is always an element of risk in any marketing spend you make. Nobody can guarantee results like ranking number 1 for your keyword. How could they when Google is independent, right? And they could get you ranking for low-quality keywords that offer no tangible RoI. Looking for certainty could end up costing you in idiot (sorry) tax.

Cheap-as-chips services. Search engine marketing (SEO and SEM) captures the largest share of online spend (almost half of online spend or 14% of the total marketing budget). Some industries spend more. It really is a case of you get what you pay for. A good agency will calculate what makes sense to spend whether you're selling a £100,000 super car or a £10 T-shirt. But if one agency comes in at a lot less than others – be suspicious.

SEO agencies operating in isolation. Your search agency should jump at the chance to be in on multi-agency planning meetings (you're inviting them in, right?). If not, it might mean that they're off on their own doing cheap black-hat tactics that get a quick result. Or, they're outsourcing so much work that they don't have an account manager available to come in to see you.

Copy-and-paste reporting. Often I see brands' search reports that are just a PDF download from Google analytics. If your agency isn't writing to you with recommendations – such as retiring ineffective campaigns, flagging high-converting keywords, or upcoming seasonal hooks – they're probably not 'optimising' your SEO at all.

And there's one thing you can do for your search agency in return. "Involve us with any website decisions or changes," pleads Morgan. "I've lost count of the number of times a client has changed, or even launched, a whole new site, without running it past us. Sometimes the negative impact can be huge when it would've been very little work for us, and cost for them, in the first place."