Very good advice given so far :)
I have seen horses that WERE hard to catch due to fear. My filly was one of them! Now, I took her on because I was told that hard to catch was her only vice. She had been raised like I see a lot of racehorses raised - that is to say, halter broke and branded as a weanling, then largely ignored until it's time for breaking. It's not uncommon for them to be kind of shy if you pick up an unraced, unbroke one. Her owner was a farrier and so he would have brought them in about every 6 weeks to look after their feet, and hers were [and are] BEAUTIFUL, so I can't fault the guy as a farrier.
When we went to pick her up, we got there and she'd already been caught [was just in the pasture when I went to look at her, couldn't get near her] and was DRENCHED in sweat and stressing badly. That was fine, she led nicely even though her friends were bolting around in the top pasture and she was about two pastures away from them. But now I look back and see a major red flag there.
But it took us an hour and a half to get this horse onto the trailer to get her home. Trailering was another vice and this one was MAJOR, she was dangerous about it, rearing up and striking out.
I'd dealt with bad floaters before too so I figured that was nothing I couldn't fix. Yes, that's right, I ignored the SECOND major red flag!
Eventually got her home after dark and she unloaded nicely but walked all over the top of me to the round pen, which I had already prepared for her to live in until I could catch her easily.
Over the next few days [that was all it took] I followed the approach and retreat method diligently. Several times a day I would go into the round pen and try to walk up to her. If she left, I would follow. She couldn't get away from me in there. If she stayed still, so would I, until she looked away. Then I would take another step towards her and repeat the dance until she stopped again. After about the second day I could easily walk up to her and rub her shoulder, neck and barrel. On the third day I introduced the halter and by the end of that day I could easily walk up to her and halter her. She wasn't consistent, not by far, but this horse that was formerly impossible to catch without backing her into a corner and manhandling her [I am neither strong enough nor willing to do that] had become possible to catch gently and without frightening her more. Took her about 3 months to become consistent.
I could have introduced the halter on day one but I think it would have taken a LOT longer to see results.
Then I discovered that my horse was dangerously terrified of doing the wrong thing, but that's a story for another thread.
Anyway, guess what I'm saying is that catching CAN be the only problem a horse has, or it CAN be a warning sign that greater issues are afoot.
MAKORA THOROUGHBRED SPORTHORSES