In ME1 and ME3, quite easily. ME1 has intimidate being a level skill, so you don't have to stick exclusively to the lower side just to persuade people. In ME3, alignment is just for show and reputation is what lets you persuade people. It's in ME2 that it's really difficult, with how persuasion in that game works. In that one, you are definitely punished for veering off your chosen morality. So you have to strike a balance between getting enough R points to do all the persuasions you want, but not picking all the R choices since doing so makes Shepard out to just be a petty jerk and criminal. If you don't know how it works in ME2 (basically, the actual amount of paragon and renegade you see in your character screen doesn't actually tell you how easily you'll be persuading people)...
http://forum.bioware...-3#entry1421404
"Actually that's very believable.Since so many people want the explanation of how this works I'll tell you. Don't read any further if you don't want it spoiled. There are potential paragon and renegade points throughout the game. When the user arrives in an area (ie: Omega) the game registers every single paragon or renegade decision that can be made and increases the difficulty of the persuade system based on these potential points. If the user collects all of these points (either paragon OR renegade) they break even they can almost never get ahead of the system, you can only keep apace. If the user misses these oppotunities to collect all of the points the game still keeps these points you missed so the player will actually fall behind. If the player falls behind it is very difficult and almost impossible to catch back up because everywhere you go more potential points are being mounted against you and making the persuasions more difficult. So when you arrive at the most difficult persuasions in the game where you are already at a disadvantage due to the difficulty of the persuade and these potential points that you missed stack up to make it even more difficult and then you try to paragon persuade jack and miranda which makes it even more difficult(it's easier to renegade persuade those two and paragon persuade legion and tali) you are going to fail it; not because it's a bug but because the system was made that way.
What I think a lot of people aren't realizing is that when you import an ME1 save you get a pretty major bonus to the paragon or renegade scale which makes the persuades incredibly easy. then you start an ME2 newgame + and you are working from a clean slate.
Hopefully that explains it well enough for you.
I've talked to the people who made this system and decided on the bonus for starting a newgame+ and the odds of this being changed or made easier are very, very low.
If you're confused by the explanation I gave or need some clarification please feel free to PM me. Thanks."