Fair enough. You can't help but be shaped by your experiences and if you've had bad advisers then you're bound to be jaded.
I am very good at what I do, even if I do say so myself.

I genuinely give a **** about my clients though, which is the absolute key in my opinion. That and having pride in everything I do.
If you have those two things in professional services (and most business actually), you won't go far wrong.
Out of interest, can you recall what the three year restriction was caused by? It could be a PAYE thing (not my area), but generally the time limits are two, four or six years for amendments, etc. in the tax world (less so with the six year windows these days).