.. down at the corner tap.. OOOOOPPPS.. wrong species..
To answer your question.. Boa are complex and diverse in ways not easily discerned.. different Boa will react to things that go unnoticed by others (and by us).
As examples some Boa hate smokers, or at least smoking makes them edgy. Many 'musk' type perfumes and cologne contain animal extracts or laboratory equivalents that frighten Boa or engage their feeding drive (BTW.. B. subocularis musk will drive most felines mad in a certain way).. temperature affects how secure a Boa feels.. the list is endless.
And all this has to be considered in the context of the fact that the captive-experience is something not allowed for in their genetic heritage at all. If you consider that fact then it would be a no-brainer to conclude that even a pretty uppity Boa is doing his darndest to get along. Or, to put it another way.. there is no such thing as a 'tame' or 'mean' Boa.. there are considerate and observant keepers and there are everybody else who complains about their mean boa. (We are supposed to be the dominat species, right?)
BUT... I admit I've seen some troublesome Boa that were hard to manage.. mostly mature females. Hands down (on average), mature males allowed to breed are the most calm of all adult Boa.. sub-mature males and females are about even.. (both like and not-alike what we see in people).
Different races and localities carry recogniseable sub-sets of behavioural characteristics! Watch them and learn!.. go to my website if you like.. I try to give some insight on this with the groups I work with.
Have a great day!!

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Gus
A. Rentfro
RioBravoReptiles.com
www.riobravoreptiles.com
"Quality is not an accident. Perfectly healthy animals are a minimum requirement.. everything else is just salesmanship" gus