When campaigning organisations commission polls you kind-of expect the results of the poll to back up their position, even if the poll is conducted by a reputable polling company.
So if, say, the People's Vote campaign or the Leave Means Leave campaign commissions a poll and the results reinforce their respective positions, then it's easy to feel wary - even if the polls are just as scrupulously-conducted as any other poll and, in all probability, just as reliable - or unreliable.
You always need to look at the question though. One of the questions Leave Means Leave put via ComRes a few days ago ran as follows:
Some have described the government's approach to Brexit as a 'stitch-up'. Reflecting on this, do you agree or disagree with the following statement?:Organisations like the BBC seem to be in favour of remaining in the EU and fail to give an impartial view on Brexit
Now, there's undoubtedly a 'leading' quality (or two) to that question. I'd prefer a simple 'Do you agree or disagreement with the following statement? The BBC reports Brexit in a biased way' kind of question (complete with follow-up questions), with none of that framing.
But, it's a question nonetheless and it was conducted by ComRes in their usual way, so - for what it's worth - the results are as follows:
42% agree that the BBC has a pro-EU, anti-Brexit bias
25 % disagree
33% don't know