What potential clients look for
It's amazing, but whether it's a small-time supplier of bathroom fixtures or the art-buyer of a major agency, they always look for the same thing. They want to see their job already done!
What I mean by that is that the bathroom fixtures supplier will want to see half a dozen sites for other bathroom fixtures suppliers. Ad agency art-buyers that I've had dealings with seem to show a similar lack of imagination and take everything most literally.
Unless you specialise in very niche market areas, it is unlikely that you will be able to show several competitor's sites. I'd be more worried about their being 'typecast' if their work was as polarised as this.
All you can do is to try to fire their (lack of) imagination by showing possibilities that they never dreamed of and by pointing-out that where the 'products' are not the same, the principles of selling them are.
I've said this before but I want to emphasise it. The initial impression is very important. A presentation that worked for one client isn't necessarily the right one for another. If you just happen to have a similar sample to the one you are pitching for, show it first. The rest is icing on the cake!
It also helps to finish up with an outstanding piece of work, no matter if it is relevant or not, it leaves your presentation on a high note instead of an anti-climax.
If nothing in your portfolio is relevant to the clients needs, you have an uphill struggle. In this case, you have to demonstrate that you understand their needs and are capable of satisfying them without resorting to visual aids. In such a case, I would try to turn it into the advantage of being a 'fresh-eye' that sees new ways of looking at things and helps produce new, creative solutions.