Hi Locksmith_in_London,
Since the Google Penguin Update, you should be really careful about the quality and relevancy of the linking page/domain to your website. So as you say, if they are unhealthy, you should in fact try to remove them as they might harm. In addition to lowering your domain/page authority, it could earn you a Google Penalty, and you really don't want that.
In order to get quality links, you should:
- Look for websites with higher authority than yours
- In addition, these websites should be relevant to your website, or linking to your website from a high quality page that contains relevant content to your page/website. For example, local business reviewing bloggers, who talk about your business could give you a high quality link.
- Make sure you don't link to your website using industry keywords as anchor links (or link text) as this is considered "Spammy". Always used your domain or your brand name.
- Don't link to your website from web directories or forums, unless the forum is discussing your services.
I see that the best people to get you these kind of links are PR agencies (but not through press release distribution systems).
I hope the above helps
Issa
Not really a strategy, but that's just me entertaining the idea of being your marketing expert.