English people often say I don't sound Scottish. I'm frequently taken for Irish (including northern irish) or West Country. I was asked if I was from Bristol a few weeks ago. In Scotland (especially in the central belt) sometimes people think I'm English.
My standard explanation: Highland accents (including Inverness) just aren't as strong as central belt accents. This I believe is partly because (unlike the lowlands) English has only been widely spoken in the highlands for a relatively short time (a few generations) so there's not been time for strong accents/dialects to develop.
As has been discussed previously here, people from the Inverness area speak the best English in the world. This assertion is based on a selective interpretation of a single academic study, if I remember right.
The other thing I've heard said about the Inverness accent is that it's influenced by Cockney due to English soldiers being posted there at some time in history. Or something. Never sure if there's any truth in that. I think I can see there are a few similarities though.
I don't even have a strong Inverness area accent anyway, possibly partly due to parents' accents and also due to going over to the dark side and living in London for two decades now. I am actually back in the Highlands just now for an extended period and am watching to see if my accent changes; I am conscious of various aspects of how I speak reverting to previous habits whenever I'm here.
My sister who grew up in identical conditions to me would be immediately identifiable to most people as Scottish though. She's lived her entire adult life in Scotland including in Glasgow so hasn't been polluted with defective speech like I have.
danny la rouge why don't you have a west highland accent then?
quimcunx has an excellent accent (don't tell her I said this or she will get a big head), a bit of a teuchterish tinge to it but I think immediately recognisable as Scottish.
(someone will tell me off for mixing up accents and dialects which are technically different things I think)