Playing SC's from blinds a big leak? (or a leak in general)

[aditya]

So I generally play a decent amount of SC's from the blinds (or just in general). I've been told it's pretty bad by some while others say it's not really as big a leak as others.

Situation 1: CO regular (tag) pops it up to 3.5BB, you're Button with 56ss or 78ss, is calling here a big leak (obv 3-betting is an option, but for all intensive purposes, lets say you decide to either fold or call.)

Situation 2: Some donkey from MP raises it up to 3.5 BB again, and another donkey in CO calls and folded to you in SB with 56ss or 78ss, is calling here a big leak? What about with hands like 68ss or 46ss?

Situation 3: Tag (nitty) regular, raises from UTG, and another TAG calls in UTG+1, folded to you in BB with 56ss or 78ss, is calling that big a leak? What about with 1 gapped suited connectors?

Gah, after posting this, it makes it sound like I'm trying to get info for free or leach but I honestly just wanna know if its a leak or if its OK?